- 8 ounces bittersweet chocolate
- 2 ounces unsweetened chocolate
- 4 ounces toasted hazelnuts
- 3 tablespoons confectioner's sugar
- 1/4 cup premium-quality Dutch-process cocoa powder
- 3/4 cup (1 1/2 sticks) unsalted butter, softened
- 3/4 cup plus 5 tablespoons granulated sugar
- 1/3 cup unsweetened hazelnut paste (available at specialty stores)
- 6 eggs, separated
- 2 teaspoons strong brewed espresso, cooled completely
- 2 teaspoons Frangelico (hazelnut liqueur)
- 2 teaspoons pure vanilla extract
- 1 Preheat oven to 325°F. Spray twelve 3-inch cake molds or one 9-inch springform pan lightly with nonstick cooking spray and set aside.
- 2 Fill the bottom of a double boiler one-third full with water and bring to a simmer over medium-low heat. Place a medium stainless-steel bowl over the water and melt the chocolates together, stirring constantly. Once melted, set aside to cool.
- 3 In the bowl of a food processor, pulse the hazelnuts with the confectioners' sugar and cocoa to form a fine, sand-like mixture.
- 4 In an electric mixer, beat the butter and 3/4 cup of the granulated sugar until very light and fluffy. Beat in the hazelnut paste, scraping down the sides of the bowl with a spatula, then beat in the egg yolks, one at a time. Beat in the espresso, Frangelico, and vanilla extract, followed by the melted chocolate. Fold in the nut mixture.
- 5 In a separate mixing bowl, use the whip attachment to beat the egg whites until foamy. Gradually add the remaining 5 tablespoons of sugar and continue beating until soft peaks form. Using a rubber spatula, gently fold the egg whites into the cake batter. Place the prepared molds on a greased baking sheet and divide the batter evenly among them.
- 6 Bake the cakes just until they puff and crack slightly, about 14 minutes for the cake molds (45 to 50 minutes if using the springform pan). Remove from the oven and cool in the molds on a wire rack. When the cakes are almost completely cool, gently remove the molds, then chill in the refrigerator until firm. The cakes will last for up to 1 week, refrigerated in an airtight container.