There are three things I want to tell you about this cake: (1) I overbaked the genoise - don't do that; (2) the white chocolate mousse was AMAZING; and (3) next time, I'm going to ditch the raspberry mousse and pair the white chocolate part with a Meyer lemon mousse and some bittersweet chocolate shavings, and we will all, ALL, be much happier.
So this cake was pretty good, but what I really want to talk about is the white chocolate mousse. Let me tell you - I don't even like white chocolate. I only bought a chunk of Callebaut because it was on sale and because melted white chocolate mixed with a little food coloring is a great way to write on cakes (I hate that gel stuff that's sold in the supermarket, yuk!). So this big hunk o' chocolate sat in my refrigerator for a while, just staring at me, until I guiltily found something to do with it. And boy, did this mousse show me! It was rich, it was creamy, it was all that white chocolate can ever aspire to be. I am definitely making it again, and I'm already seeing visions of cold, delicate white chocolate sweetness paired with something bitter or tart - anything, really - Meyer lemon mousse, tart cherry cheesecake, dark chocolate... I've gained some respect for white chocolate and I'm going to find a worthier use for the other half of my stash than cake decoration.
White Chocolate Raspberry Mousse Cake
This cake is made of 3 components - a basic genoise cake recipe, raspberry mousse and white chocolate mousse. I didn't like the raspberry mousse recipe I used, so I'm not going to give it to you, but the cake and the white chocolate mousse were damn good.
Basic Genoise Cake by Flo Braker
Makes 1 9-inch cake (I halved the recipe to make a thin layer of cake)
2 tablespoons unsalted butter, melted
4 large eggs, room temperature
1/2 cup sugar
1 teaspoon vanilla
1/8 teaspoon salt
1 cup sifted cake flour
*Framboise for brushing the cake layer
Position rack in lower third of oven; heat to 350°. Grease and flour a 9-inch cake pan; set aside.
Melt butter in small saucepan over low heat. Pour into small mixing bowl; set
nearby. Mix eggs, sugar, vanilla and salt in a large mixing bowl. Using an electric mixer, whip egg mixture until it has tripled in volume, about 4 to 5 minutes.Fold flour into mixture, one third at a time, just until incorporated. Pour about 1 cup of batter into the melted butter, and fold just until combined. Return butter mixture to reserved batter, and again fold to combine.
Pour batter into prepared pan. Smooth batter evenly. Bake 20 to 22 minutes or
until top springs back slightly when lightly touched. Cool 10 minutes, then run a table knife blade around the outside edge of cake, freeing the sides and allowing air to get under the layer. Invert cake onto rack and allow to cool completely.
White Chocolae Mousse(Gourmet, April 1990)
*Note that this mousse consists of a batch of pastry cream (the first 6 ingredients), melted white chocolate and whipped cream. The pastry cream is meant to be divided in 2, half for the white chocolate mousse and half for the raspberry mousse. If you are only making the white chocolate mousse, halve the first 6 ingredients to make half a batch of pastry cream.
4 large egg yolks
1/3 cup sugar
3 tablespoons cornstarch
1 1/2 cups milk
2 teaspoons vanilla extract
3 tablespoons unsalted butter, softened
9 ounces fine-quality white chocolate, chopped
1 cup heavy cream
Make the pastry cream: In a bowl whisk together well the yolks, the sugar, and a pinch of salt, add the cornstarch, sifted, and whisk the mixture until it is just combined. Bring the milk almost to a boil, then slowly drible about 1/4 cup of the hot milk into the eggs, whisking to prevent the yolks from cooking. When the yolks are thus tempered, you can add them to the rest of the hot milk. Boil the mixture, whisking, for 1 minute, or until it is very thick and smooth. Strain the pastry cream through a fine sieve into a bowl, stir a few times to release the steam, and then stir in vanilla and the butter (one tbsp at a time). Press plastic wrap to the surface of the pastry cream and chill until it's cooled completely. Divide the pastry cream in half (if you have made a full batch). Set aside one half for the white chocolate mousse (about 1 cup) and reserve the other half.
Add in white chocolate and whipped cream: In a heat-proof bowl set over barely simmering water, melt the white chocolate, stirring occasionally, and let it cool to lukewarm. In a large bowl whisk together the white chocolate and the 1 cup of the pastry cream, until the mixture is combined well. In a bowl with an electric mixer beat the heavy cream until it holds soft peaks, whisk one fourth of it into the white chocolate mixture, and fold in the remaining whipped cream gently but thoroughly.
To assemble the cake: Line the sides of an oiled 9-inch springform pan (or a 9-inch cake ring) as smoothly as possible with pieces of plastic wrap (the plastic wrap prevents the filling from discoloring and makes unmolding the cake easier), letting the excess hang over the side.
If you've made the full recipe of the genoise, divide it in half. Fit one half on the bottom of your mold. Brush the cake with about 2 tablespoons of Framboise, and spread it evenly with the white chocolate mousse. If this is all you are making, cover the cake loosely with plastic and set in the refrigerator for at least 4 hours.
If you are using a second type of mousse (i.e., lemon or raspberry), let the white chocolate mousse set in the refrigerator for an hour before spreading the second mousse on top. If you are using the second half of the genoise, set the second layer either between the mousse layers or on top of the cake. Let chill in the refrigerator for at least 4 hours.