Is it “the best chocolate cake in the universe?” You decide.
4 eggs separated
1 cup granulated sugar
4 ounces unsweetened chocolate
12 tablespoons (1 1/2 sticks) sweet butter
1 cup plus 1 tablespoon cake flour
1/4 teaspoon salt
3 tablespoons very finely ground skinned hazelnuts
Beat egg yolks and sugar together until mixture is thick and pale yellow. Meanwhile, in the top of a double boiler set over simmering water, melt the chocolate with the butter, whisking constantly until smooth; cool slightly.
Preheat oven to 350 degrees. Grease an 8-inch springform pan. Line the bottom with a circle of wax paper. Grease the paper and lightly flour lining and sides of pan. Pour chocolate-butter mixture into egg mixture and stir just to blend. Fold in flour, salt, and ground hazelnuts. Whip egg whites until stiff and fold gently into batter.
Pour the cake batter into prepared pan and rap the pan lightly on a work surface to eliminate any air bubbles. Set on the middle rack of the oven and bake for 35 to 40 minutes, or until edges are firm and inside is set but still somewhat soft. Do not worry if top cracks slightly. Cool in the pan, set on a rack, for 1 hour. Remove sides of pan and cool cake to room temperature.
When cake is cool, invert it onto a serving plate and spread top and sides with hazelnut buttercream (see below). Refrigerate cake for 30 minutes.
Remove cake from refrigerator and spread top and sides with warm chocolate icing (see below). Work quickly, as icing sets. Refrigerate the cake for at least 1 hour before cutting and serving.
1 1/4 shelled hazelnuts
5 tablespoons corn syrup
2 tablespoons brandy
1 cup confectioners’ sugar
4 tablespoons unsalted butter, softened
Roast hazelnuts on a baking sheet in a 350-degree oven for 10 to 15 minutes. Remove nuts from oven and rub between towels to remove skins. Transfer to the bowl of a food processor fitted with a steel blade and process until nuts begin to form a paste, peanut butter-like in texture. Scrape paste into a bowl and stir in corn syrup and brandy. Let sit for 20 minutes. (Can be prepared in advance and refrigerated. Let return to room temperature before proceeding with recipe.)
Cream confectioners’ sugar and butter together until light and fluffy. Add hazelnut paste and mix thoroughly.
4 tablespoons sweet butter
4 ounces semisweet chocolate
3 tablespoons cream
2/3 cup sifted confectioners’ sugar
1 teaspoon vanilla extract
Melt butter and chocolate together in the top part of a double boiler over simmering water, whisking constantly. Remove pan from heat and beat in cream. Sift in confectioners’ sugar and vanilla. Icing should be very smooth. Spread while warm.