The recipe

It's no longer my birthday but the memory of my birthday cake still holds. There is a small piece left in the refrigerator which will be eaten tonight, shared between S and me, but I can assure you that there will be a fight over the last bite.






I'm certain you've been drooling over this amazing cake and I wouldn't dream of leaving you without a recipe—it wouldn't be fair. It's one of the best cakes I have ever tasted and as I've said many times before, a good thing needs to be shared.






This is a triple chocolate cake. The bottom layer is a dark chocolate flourless cake with a subtle coffee flavor that comes from the addition of espresso powder. The middle layer is a dark chocolate mousse without eggs that is as light as a mousse can get and the top layer is a white chocolate mousse, again without eggs but with the addition of gelatin which holds the mousse together. Since white chocolate has more fat in it, it's more difficult to set in the form of mousse and become easily sliceable, so the gelatin works wonders in this respect. It also gives the mousse a more dense texture, distinguishing it from the more fluffy, airy middle layer of dark chocolate mousse.






The textures and flavors of this cake are unbelievable. There is a complete balance of flavors without any one layer overpowering the other two, each chocolate flavor being distinct and utterly delicious. The textures of each layer are all different from one another thus composing the perfect sweet cake bite.






Admittedly, this cake is not easy to prepare. The fact that I have a stand mixer surely helped me a lot but that doesn't mean that you can't complete the task with only a hand held mixer. It will just be more time consuming.






What's great about this cake—apart from the fact that it tastes and looks divine and that it is the best birthday cake ever—is that once you've made it, you realize that you now know how to make not one, but four different types of desserts. a) The actual cake, b) a flourless chocolate cake which you can make all on its own and serve it drizzled with melted chocolate or you can spoon some créme fraiche on top, c) a light, easy dark chocolate mousse that you can whip up in no time, since it doesn't have any eggs in it, chill it in the fridge in individual ramekins and serve it with a dollop of whipped cream and, last but not least d) a white chocolate mousse which you can serve in small bowls with dark chocolate shavings sprinkled on top. Is that fantastic or what?












Triple Chocolate Cake
Adapted from America's test kitchen

It is best that you make the cake the day before you want to serve it because it needs to be refrigerated for several hours.

It is important that you use good quality chocolate for all three layers.






Yield: 1 cake / 12-14 servings

Ingredients

for bottom layer (flourless chocolate cake)
85 g unsalted butter, cut into small pieces plus extra for greasing the pan
200 g dark 70% chocolate, cut into small pieces
1 tsp espresso powder
4 large eggs, separated into egg yolks and egg whites
Pinch of salt
75 g soft light brown sugar

for middle layer (dark chocolate mousse)
2 Tbsp Dutch-processed cocoa powder
75 ml hot water
200 g dark 55% chocolate, cut into small pieces
350 ml cream, full-fat, cold
20 g (1 Tbsp) caster sugar
1/8 tsp salt

for top layer (white chocolate mousse)
1 gold gelatin leaf (2-2.2 g)
250 ml water
170 g good quality white chocolate (at least 28% cocoa butter), cut into small pieces
350 ml cream, full-fat, cold

Dark and white chocolate shavings or cocoa powder for garnishing the top of the cake

Special equipment: 24 cm round spring-form cake pan with height at least 7.5 cm (and a 22 cm spring-form pan—see update), stand mixer or hand held mixer, offset spatula


Preparation

for bottom layer (flourless chocolate cake)
Butter generously the sides and bottom of the spring-form pan.

Preheat your oven to 160 degrees Celsius.

Melt butter, chocolate and espresso powder in a bowl set over a pan of barely simmering water, stirring often and making sure the chocolate doesn't burn. The bottom of the bowl must not come in contact with the simmering water. Once the mixture is smooth and melted, remove bowl from the top of the pan and set aside to cool slightly, about 5 minutes.

In a large bowl, add the four egg yolks and beat them lightly with a whisk. Add a spoonful of the melted chocolate mixture to the egg yolks and whisk just until incorporated. Add little by little the rest of the melted chocolate to the egg yolks, whisking just until incorporated. If your mixture looks lumpy or a bit curdled, do not worry. Once you incorporate the beaten egg whites into it, it will be ok. Set aside.

Note: You can add the egg yolks directly to the slightly cooled melted chocolate but you run the risk of having a lumpy mixture or, even worse, a split mixture.

In the bowl of a stand mixer fitted with the whisk attachment (or in a large bowl and with a hand held mixer), beat the four egg whites and salt at medium speed until frothy, for about 40 seconds. Add half of the brown sugar, after you have crumbled it with your hands to remove any lumps, and beat at medium speed until combined, for about 20 seconds. Add the remaining brown sugar, after you have crumbled it with your hands to remove any lumps, and beat at high speed until soft peaks form when you lift the whisk, for about 1 minute longer.

Using a whisk, fold one-third of the beaten egg whites into the chocolate-egg yolk mixture in order to lighten it up. Switching to a rubber spatula, fold in carefully the rest of the beaten egg whites until no white streaks are visible.

Transfer the batter carefully into the buttered spring-form pan, tap it gently so that it spreads evenly around the pan and smooth the top using an offset spatula. Place the pan carefully on the middle rack of the oven and bake until the cake has risen and is firm around the edges and soft but springy to the touch in the middle, for 13-17 minutes.
Transfer cake to a wire rack to cool completely, about 1 hour. Don't remove the cake from the pan and keep in mind that the cake will collapse as it cools.

Note: My cake, apart from collapsing, it also shrank considerably, leaving a gap between the edges of the spring-form pan and the cake. I have no idea why this happened but I had to move my cake to another pan in order to be able to create the other layers on top of it. I moved it carefully (I had buttered the bottom and sides of the pan well so this helped) in a 22 cm spring-form pan and continued with the rest of the layers.

Update 06.11.2011: I have made this cake several times since I posted the recipe, and I have to say that every single time, the cake shrank. That's the nature of the cake. So, I suggest you bake the cake in a 24 cm pan and then, once cooled, move it to a 22 cm pan. Continue building the mousse layers of the cake into that pan.


for middle layer (dark chocolate mousse)
Dissolve cocoa powder in the hot water inside a small bowl and set aside.

Melt the chocolate in a bowl set over a pan of barely simmering water, stirring often until smooth. Remove bowl from the top of the pan and let cool slightly.

In the clean bowl of your stand mixer fitted with the whisk attachment (or in a large bowl and with a hand held mixer), beat cream, granulated sugar and salt at medium speed until mixture begins to thicken, for about 40 seconds. Then increase speed to high and whip until soft peaks form when you lift the whisk, for about 1 minute.

Whisk cocoa powder mixture into the melted chocolate until smooth and using the same whisk, fold one-third of the whipped cream into the chocolate mixture to lighten it up. Switching to a rubber spatula, fold in the rest of the whipped cream until no white streaks are visible.

Transfer mousse into the spring-form pan, over the cooled cake, and gently tap the pan on the counter in order to remove any large air bubbles. Smooth the top of the mousse with an offset spatula and wipe clean the inside edges of the pan to remove any drips.

Put pan in the refrigerator for at least 1 hour in order for the mousse to set.

for top layer (white chocolate mousse)
Place the gelatin leaf in a small bowl and add the water on top. The water must cover the leaf completely. Soak for 15-20 minutes until the gelatin softens.

Place white chocolate pieces in a medium-sized bowl.

In the meantime, pour 120 ml of the cream inside a small saucepan and bring to a simmer over medium-high heat. Don't let the cream boil. Remove the pan from the heat and add the softened gelatin to the cream. Stir with a rubber spatula until the gelatin dissolves completely.

Pour cream mixture over the white chocolate and whisk until chocolate is melted and you have a smooth mixture. Let it come to room temperature, stirring every 5 minutes or so. The mixture will slightly thicken.

In the clean bowl of your stand mixer fitted with the whisk attachment (or in a large bowl and with a hand held mixer), beat the rest 230 ml of cream at medium speed until mixture begins to thicken, for about 40 seconds. Then increase speed to high and whip until soft peaks form when you lift the whisk, for about 1 minute.

Using a whisk, fold one-third of the whipped cream into the white chocolate mixture, in order to lighten it up. Switching to a rubber spatula, fold in carefully the rest of the whipped cream until no white streaks are visible.

Transfer white chocolate mousse into the pan, on top of the set dark chocolate mousse. Smooth the top with an offset spatula and return cake to the refrigerator to set. Chill the cake for at least 4 hours but it's best if you leave it in the fridge overnight.

serve the cake
Once set, remove cake from the fridge and run a knife around the sides of the pan in order to release the cake. It is best if you do this in one smooth motion so the cake doesn't have markings from the knife, especially since it is a mousse cake thus being more delicate.
Remove the sides of the pan. You can run a clean knife along the outside of the cake to smooth the sides. Don't remove the cake from the bottom of the pan.

Before serving the cake, you can add dark and white chocolate shavings on top or even sprinkle it with cocoa powder. Cut the cake into slices—it would be best if you didn't use a knife to do that but a cheese wire or even dental floss.
Serve and enjoy!

You can keep the cake in the refrigerator, covered with cling film, for up to 5 days.