Chocolate Swiss Roll (巧克力瑞士蛋糕卷)

If you've never made Swiss roll before, or never made one successfully, please don't try my chocolate Swiss roll recipe.

Making chocolate Swiss roll is a bit tricky. Why? Because cocoa powder complicates things. If you want a straightforward recipe, go for vanilla roll. That's almost idiot-proof (not that idiots are the lowest common denominator).

Cocoa powder makes the cake less stretchable, so you have to be careful not to overbake the cake. Even slight overbaking makes the cake crack when you roll it.

Cocoa powder also makes the crust sticky, so you have to be careful not to underbake the cake. The more underbaked the crust is, the stickier it is.

The cake is perfectly done when it just turns springy in the middle. After it's cooled down, the crust should be a bit sticky around the edges. That's OK because the ends will be trimmed, or tucked inside/below after the cake is rolled.

If the entire crust isn't sticky, that's not a good thing at all. The cake is too dry and will likely crack when you roll it.

If the entire crust is sticky, it's gonna stick to whatever it rests on. Of course, that's not a problem if you ice the cake. Or if you go for the skinless look and roll the cake inside out.

Even when you've got the cake baked just right, you may still have a problem when you're rolling the cake. Why? Because the crust doesn't really stick to the crumb, so it comes off very easily. The loose crust is caused by cocoa powder which, as I said, complicates things.

Chocolate cakes have haphephobia (fear of being touched). Direct contact with the crust must be minimized if you don't want to damage it. How? Like this:

⋈ Put the cake on a piece of parchment paper, face down. Spread with whatever filling you like.

⋈ Start rolling the cake by making a fold in the cake. The fold must be very small, or the cake will be oval instead of round after rolling.

⋈ After the first fold is tucked in tightly, lift and tilt the parchment paper with your left hand (if you're right-handed). As the cake moves forward, it may bulge here and there. Gently flatten the bulges with your right hand so that the roll is tight and even. If you're making a very long roll, you'd need a rolling pin (or the core of your parchment paper or aluminium foil) to do this.

Because the cake doesn't handle well, it cracks (when you roll it) if it's too thick. And if it's too thin, the inside may be too dry when the crust is just right. Hence, you must scale the recipe according to your pan size. You don't want too little or too much batter in the pan. 

Why make such a fuss over a cake? Why not just let it crack? You can hide the cracks with icing, icing sugar, chocolate rice/shavings, nuts, whatever. Nobody would know, right?

Yup, covering up is an easy way out. But you'd have bought a chocolate Swiss roll if you had wanted the easy way out. Or at least made a Swiss roll without cocoa powder. Or just eat the bloomin' cake without rolling it!

For those who want to make a good but uncomplicated Swiss roll, click here for my vanilla recipe.  For those who want to make a chocolate roll for the sake of making it, because eating is only half the fun:

CHOCOLATE SWISS ROLL (巧克力瑞士蛋糕卷) (Recipe for one 12" roll) 15 g corn oil 10 g alkalized cocoa powder, Green & Black's brand 15 g castor sugar 10 g water pinch salt 1/2 tsp vanilla extract 30 g egg yolks 15 g cake flour 70 g egg whites 30 g castor sugar 75 g whipped cream If you double the recipe, you need a pan that's 18"x 12". 1. To make cake, preheat oven to 200°C. Measure and prep ingredients as detailed above. Grease 12" x 9" pan with butter. Line pan with 12" x 12" parchment paper. 2. Heat oil till hot but not smoking (if you put your hand near the oil, you should feel searing heat). Add to cocoa powder. Whisk thoroughly. Add 15 g castor sugar. Whisk thoroughly. Add water. Whisk till thick paste forms. Add salt, vanilla extract and egg yolks. Whisk till sugar dissolves. Sift half of cake flour into mixture. Mix with whisk till even. Sift remaining cake flour into mixture. Mix with whisk till even. 3. Whisk egg whites on medium-slow speed till thick foam forms. Gradually add 30 g castor sugar whilst continuing to whisk. Keep whisking till egg whites are at soft peak stage. Reduce speed to slow and continue to whisk till firm peak stage (when whisk is lifted, egg whites form peak that's hooked). 4. Loosen egg yolk mixture from bottom of mixing bowl with whisk. Add egg whites in 2 batches. Mix with whisk after each addition till batter looks even. Scrape down and fold with spatula till batter is truly even. 5. Pour batter into cake pan. Spread with spatula as evenly as possible, pushing batter into corners of pan. Jiggle vigorously till batter is level. Tap pan against worktop twice. 6. Bake cake on middle shelf till middle of cake is springy when pressed, about 10 minutes. Remove from oven. Drop pan from 1' high 3-4 times. Unmould cake onto wire rack. Peel parchment paper from sides of cake. Leave till cool. 7. To assemble Swiss roll, place cake on clean parchment paper, face down. Peel parchment paper from bottom  of cake. Spread evenly with whipped cream. Roll cake as shown in video. Do not remove parchment paper till cake is transferred to serving plate (so that cake may be moved easily without touching the crust). 8. To cut Swiss roll neatly, chill till filling is set. Cut with serrated knife, wiping knife clean with paper towels after each cut. Transfer to serving plate. Discard parchment paper. 9. To store overnight, place Swiss roll in cake pan. Place pan in plastic bag, making sure bag doesn't touch Swiss roll. Refrigerate. Remove from fridge about 15 minutes before serving. Cut immediately. Transfer to serving plate. Discard parchment paper. Serve when cake is soft but filling is still cold.

Vanilla Swiss Roll (香草瑞士蛋糕卷)

There're a few common problems with making Swiss rolls: (1) The cake is hard and dry. (2) The crust sticks to the paper the cake is wrapped in. (3) The crust cracks when you roll the cake.

Good Swiss roll starts with, of course, a sheet cake that's fluffy. You know what's wrong with a lot of Swiss roll recipes? They have way too much flour.

A cake that's 1-2 cm tall should have very little flour because it doesn't need much structural support. If it has as much flour as a cake that's 5-7 cm tall, it would be dense and hard.

There's no point in baking a cake that's fluffy but dried out. What makes my cake moist? Oil. It has more oil than flour. If you're on a low-carb, high-fat diet, this is the cake for you!

Water doesn't help make a sheet cake moist. Why? Because the cake is so thin, H₂O in the batter evaporates very quickly. It's gotta be fat that keeps the cake moist. 

Of course, don't overbake the cake or it'll be dry no matter how much fat it has. Timing is critical because a 1-2 cm thick cake may overbake in 1-2 minutes. Make sure the cake is removed from the oven once the middle is springy when pressed lightly.

How to stop the crust from sticking to the paper it's wrapped in? Easy. Just don't wrap the cake in paper.

A lot of Swiss roll recipes tell you to roll the cake whilst it's piping hot, when it's most flexible and least likely to crack. This (the rolling, not telling) is done after placing the cake on a piece of parchment paper, and then dusting the crust with icing sugar.

The cake is rolled along with the paper, which stops the cake from sticking to itself.

The sugar is supposed to stop the crust from sticking to the paper, in theory. In practice, however, it doesn't because the cake releases moisture as it cools down. The paper traps the moisture that makes the crust wet and, hence, sticky.

How about wrapping the cake in a tea towel which breathes better than parchment paper? That works if the cake is quite dry when it's removed from the oven. But who wants a dried out Swiss roll, right? If it's moist as it should be, it'd still stick to the tea towel.

I let my sheet cake cool down on a wire rack after it's baked, without rolling or covering it.

Is my cake dry after it's cooled down? Not at all, because it has loads of fat and it's not overbaked.

Does my cake crack when I roll it after it's cooled down?

Nope, it doesn't because it's very flexible. The cake can stretch and bend into a roll without breaking. The flexibility is due to the way the eggs are beaten. The whites are whisked to firm peak stage, then the yolks are added one at a time and whisked thoroughly. Compared to the whole egg or chiffon method, this makes a cake that's more stretchable.

Some people wrap their Swiss roll, after rolling, to set the shape. If you want to do that, I suggest you use a tea towel. Parchment paper, if tightly wrapped around the cake for a few hours, will stick to the crust.

I prefer not to wrap the cake. There's really no need to do so provided the filling is firm when I'm rolling the cake.

If you use dairy cream filling, it must be firm when you're spreading it on the cake. And you must work quickly so it's still firm when you roll the cake. If it isn't, put the cake in the freezer for five minutes or so.

Here's how I make a Swiss roll (without pushing him down a mountain):

VANILLA SWISS ROLL (香草瑞士蛋糕卷) (Recipe for one 13" roll) Cake 140 g egg whites 60 g castor sugar 60 g egg yolks 40 g cake flour 1/16 tsp fine salt 1 tsp vanilla extract 60 g corn oil butter for greasing pan Filling 80 g chocolate spread       or 215 g whipped cream (click here for recipe) 1 can (312 g) mandarin orange, drained and chilled This recipe is double the pygmy-sized cake in the video. 1. To make cake, preheat oven to 200°C. Measure and prep ingredients as detailed above. Grease 13" x 10" pan with butter. Line pan with 13" x 13" parchment paper. 2. Whisk egg whites on medium-slow speed till thick foam forms. Gradually add castor sugar whilst continuing to whisk. Keep whisking till egg whites are at soft peak stage. Reduce speed to slow and continue to whisk till firm peak stage (when whisk is lifted, egg whites form peak that's hooked). 3. Add yolks to whites in 4 batches. Whisk on slow speed till evenly mixed after each addition. Sift half of cake flour into mixture. Add salt. Mix with whisk till almost even. Sift remaining cake flour into mixture. Mix with whisk till just even. Add vanilla extract and corn oil. Fold with spatula till just evenly mixed, banging mixing bowl against worktop 2-3 times. 4. Pour batter into cake pan. Spread with spatula as evenly as possible, pushing batter into corners of pan. Jiggle till batter is level. Tap pan against worktop twice. Bake on middle shelf till middle of cake is springy when pressed, 10-11 minutes. Remove from oven. Drop pan from 1' high 3-4 times. Unmould cake onto wire rack. Peel parchment paper from sides of cake. Leave till cool. 5. To assemble, place cake on new sheet of parchment paper, face down. Peel parchment paper from bottom of cake. Spread evenly with chocolate spread or whipped cream. Place mandarin orange, if using, in middle of cake. Roll cake as shown in video. 6. To cut chocolate spread Swiss roll neatly, dip serrated knife in hot water before each cut and wipe dry/clean with paper towel. For orange and cream Swiss roll, chill till cream filling is set, then use a serrated knife that's wiped clean after each cut. 7. Orange and cream Swiss roll is best eaten after an overnight rest in the fridge, when the filling has had time to perfume the cake. Chocolate spread Swiss roll should be chilled or eaten once it's made. Otherwise, oil separates from the spread and seeps into the cake, making it hard.

Fluffy Chocolate Sponge Cake (巧克力海绵蛋糕)

Ladies and gentlemen, please meet my seized chocolate cake:

Seized?

Don't worry, I haven't seized anything from anyone. It's cocoa powder that's doing the seizing, not me.

My very soft and fluffy chocolate cake is made with cocoa powder that's mixed with hot oil. The scalding helps bring out the chocolate flavour. Of course, I use high quality cocoa powder or there wouldn't be any flavour to bring out.

When the oil and cocoa combo is not too hot and not too cold, I add a little bit of milk. This is when the seizing happens, i.e. the small cocoa particles absorb the milk, become sticky, and stick to one another to form bigger particles, resulting in a thick paste. The thickness of the cocoa paste is crucial to the success of chocolate sponge cake.

If the cocoa powder isn't seized at all, it'd be suspended in a runny liquid, which will sink to the bottom of the pan during baking. The cake will be pale and bland except for the bottommost 2 mm or so. If that thin layer is stuck to the pan or parchment paper after unmoulding, then the cake doesn't taste of chocolate at all.

If the cocoa powder is "over-seized", it becomes too coarse and will look like ground black pepper in the cake. The colour of the crumb, light brown with specks of black, won't look right. There will be some chocolate flavour but it'll be weak.

When the thickness of the cocoa paste is just right, the chocolate flavour is strong and spread evenly in the cake. And the cake's colour is a nice medium-brown, not pale.

How do you control how much the cocoa powder seizes? By watching the temperature. The hotter the oil and cocoa powder mixture is when milk is added, the stronger the seizing. The right moment for adding the milk is when the bowl holding the mixture doesn't feel hot but is still quite warm.

Of the various types of cake I bake, chocolate sponge rises the most, more than even chiffon cakes. The batter more than doubles in height in the oven. After shrinking a bit whilst cooling down, the cake is twice as tall as before baking. The more the batter rises, the fluffier the cake, right?

To make the batter rise as much as possible, the bottom of the pan should have more heat than the top. Separate controls for the oven's top and bottom heating elements would be very handy. If your oven isn't so fancy, as mine isn't, just bake the cake on the bottom instead of middle shelf.

After baking comes eating. When the chocolate sponge is unadorned and still warm, the fluffiness really shows through. If you are a chocolate fiend, you could cover or sandwich the cake with ganache. Whipped cream or buttercream, whether plain or chocolate-flavoured, is quite nice too. Do you like black forest cake? A sexed up chocolate cake would be ideal for a celebration.

Compared to my vanilla sponge and pandan sponge recipes, chocolate sponge is easier. The batter is more stable because it has less egg white, so it doesn't deflate easily. With this recipe, I think even a novice baker can bake a chocolate cake that's soft, fluffy, moist and chocolatey . . . if he/she follows the instructions. That's not too difficult . . . is it?



12 December 2013 Update
Here's a video to explain why glucose helps make cakes fluffy:
 

CHOCOLATE SPONGE CAKE (巧克力海绵蛋糕) Source: adapted from FoodHouse8 (Recipe for one 20 x 12 x 5 cm cake) 25 g corn oil 10 g Dutch-processed cocoa powder 10 g milk, cold ⅛ tsp salt ½ tsp vanilla extract 10 g glucose 105 g whole eggs 15 g egg yolk 80 g castor sugar 50 g cake flour ⅛ tsp baking soda butter, softened, for greasing Measure ingredients as detailed above. Grease 20 x 12 x 5 cm cake pan with butter. Line pan with parchment paper. Generously grease paper. Preheat oven to 170°C. Heat oil till very hot, almost smoking. Add to cocoa powder. Mix thoroughly. (There should be a chocolate aroma. If there isn't, either your oil isn't hot enough or you've got crap cocoa powder, or both.) Let mixture cool down slightly, till bowl doesn't feel hot but is still quite warm. Add milk. Stir thoroughly. (You should now have a smooth or slightly grainy paste that coats sides of bowl thickly.) Add vanilla extract and salt. Stir again. Set aside to cool down completely. Whisk glucose, eggs and yolk till starting to thicken. Gradually add castor sugar whilst still whisking. Continue to whisk till mixture is thick and pale, reducing speed towards the end to remove big air bubbles. Add cocoa paste in 2 batches. Whisk till you don't see any streaks of cocoa after each addition. Thoroughly scrape bottom of bowl with spatula and fold till evenly mixed. Sift cake flour and baking soda into bowl in 2 batches. Mix with whisk after each addition, stirring just top part of egg mixture. Scrape down and fold with spatula till just evenly mixed, banging mixing bowl against worktop 2-3 times. Pour batter into cake pan. Tap pan against worktop 2-3 times. Bake in bottom of oven till batter doesn't move when gently jiggled, about 20 minutes, rotating pan as necessary so that cake rises evenly. Transfer to middle of oven. Continue baking till skewer inserted into centre of cake comes out clean, 5 minutes or so. Remove cake to wire rack. Wait a few moments. When top of cake starts to wrinkle, unmould. Peel paper from sides of cake. Leave cake on wire rack to cool down. Cut with serrated knife. Remove paper from bottom of cake. Dig in.