Makes: At least 10 servings
Time: About 3 hours
This is the type of cake you usually eat only at restaurants, but there’s no reason not to make it at home. Yes, it’s time consuming, but the end result—a smooth, rich torte, like Nutella in cake form—is totally worth the effort. Plus, its dense layers keep the cake impossibly moist; you’ll reap the rewards for the better part of a week. If you like, top it with Chocolate Ganache or Chocolate Ganache Glaze or just top the slices with Whipped Cream.
1. Heat the oven to 350°F. Butter the bottom and sides of a 9-inch round cake pan; cover the bottom with a circle of wax paper or parchment, butter the paper, and flour the pan.
2. Melt the chocolate with ½ cup water over low heat and set aside to cool. Whisk together the flour, ground hazelnuts, and salt in a medium bowl.
3. Use an electric mixer to beat the whole eggs until light; gradually add ¾ cup sugar, continuing to beat until the mixture is very thick. Gently stir in the flour mixture, then the melted chocolate, and finally 1 teaspoon of the vanilla. Gently fold in the toasted hazelnuts.
4. Turn the batter into the prepared cake pan and bake until the cake is firm and a toothpick inserted into the center comes out dry or with a few moist crumbs, 40 to 50 minutes. Cool for 5 minutes before turning out onto a rack to finish cooling.
5. To make the filling, put the egg yolks in a blender. Add the remaining 2 tablespoons sugar and 1 teaspoon vanilla and the cocoa powder. Turn on the blender and add the butter, a little at a time. After the butter is blended in, refrigerate until the filling is spreadable, at least an hour.
6. When the cake is completely cool, cut it in half horizontally with a serrated knife. Spread the bottom layer with the chilled filling, then put the top layer in place. Chill for an hour or so and then, if you like, frost or glaze. Cover with plastic wrap and refrigerate for at least a couple of days.
CHOCOLATE-CHOCOLATE TORTE For chocolate purists: Substitute an additional ¼ cup all-purpose flour for the ground hazelnuts. Swap out the toasted hazelnuts for ½ cup chopped dark chocolate.
CHOCOLATE–PEANUT BUTTER TORTE Omit the ground hazelnuts and increase the flour to 1 cup. Omit the toasted hazelnuts. Melt ¼ cup smooth peanut butter with the unsweetened chocolate mixture, stirring to combine. If you like, spread Peanut Buttercream over the bottom layer of cake instead of the chocolate filling.
SACHERTORTE A classic Viennese cake, invented in 1832: Increase the flour to 1 cup; omit the ground hazelnuts, toasted hazelnuts, and chocolate filling. Using a serrated knife, cut the cake evenly into 3 layers if you like. Heat ⅓ cup apricot preserves and 3 tablespoons water over low heat until combined; let cool. Spread the apricot glaze over the bottom and middle layers of the cake and assemble as directed, topped with Chocolate Ganache or Chocolate Glaze.
CHOCOLATE-RASPBERRY TORTE A fantastic chocolate-fruit combination: Follow the preceding variation, swapping raspberry jam for the apricot preserves.
CHOCOLATE-GINGER TORTE For a bit of unexpected spice: Omit the ground hazelnuts and increase the flour to 1 cup. Whisk ½ teaspoon ground ginger into the flour mixture. Swap out the toasted hazelnuts for chopped candied ginger. Fill with a thin layer of Ginger Buttercream instead of the filling.