1 Candied Hazelnuts and Chocolate Curls Recipe
You can bake the cake up to three days ahead; cool completely and keep at room temperature, wrapped well in plastic. The chocolate curls and candied nuts will also keep for up to 3 days in separate airtight containers.
3 cups Hazelnuts (about 13 ounces)
Preheat oven to 350 degrees. Butter a 9-inch springform pan; dust with cocoa, tapping out excess. Toast nuts in a single layer on a rimmed baking sheet, shaking occasionally, until fragrant, about 12 minutes. Transfer to a clean kitchen towel; rub to remove skins. Place any unskinned hazelnuts back in the oven for a few minutes and then run again to remove skins. Let cool.
1/4 cup plus 2 tablespoons Granulated Sugar
1 2/3 cups All-Purpose Flour
1 1/2 teaspoons Baking Soda
1/4 teaspoon Salt
2/3 cup Unsweetened Cocoa Powder (plus more for pan)
2/3 cup boiling Water
In a food processor, pulse one-third of the nuts with granulated sugar just until finely ground. (Reserve remaining nuts for the garnish; recipe follows.) Transfer to a large bowl; stir in flour, baking soda, and salt. Whisk together cocoa and boiling water in a heatproof bowl until smooth. (Mixture will thicken as it cools.)
1 2/3 sticks Unsalted Butter (room temperature; plus more for pan)
1 3/4 cups Packed Dark Brown Sugar
4 large Eggs (at room temperature)
With an electric mixer on high speed, beat butter and brown sugar until pale and fluffy, 3 to 5 minutes. Add eggs, 1 at a time, beating until well combined.
1 1/3 cups Buttermilk (at room temperature)
2 1/2 teaspoons pure Vanilla Extract
Stir buttermilk and vanilla into cocoa mixture. With mixer on low speed, add flour mixture to butter mixture in 2 batches, alternating with cocoa mixture; beat just until combined (do not overmix).
Transfer batter to prepared pan; smooth top with an offset spatula. Bake until a cake tester comes out clean, 60 to 70 minutes. Transfer pan to a wire rack to cool 10 minutes. Turn out cake onto rack to cool completely.
1 Whipped Ganache Frosting Recipe
Place cooled cake on a 9-inch cardboard round. Spread whipped ganache frosting smoothly on top and sides of cooled cake. Refrigerate until firm, about 30 minutes.
1 Chocolate Ganache Glaze Recipe
Place cake (still on cardboard round) on a wire rack set over a parchment-lined rimmed baking sheet. Using a small ladle and a circular motion, pour ganache over top of cake, letting ganache run down the sides (use an offset spatula to spread evenly, if needed). Let stand at room temperature up to 2 hours. Garnish with candied nuts and chocolate curls before serving.