Triple Hazelnut Cake with Chocolate Buttercream Frosting Recipe

Ingredients

• Shortening, for greasing pans
• 2 tablespoons cake flour, plus 3 1/3 cups, divided
• 4 large eggs, at room temperature, lightly beaten
• 1/3 cup hazelnut-flavored liqueur (recommended: Frangelico)
• 1 teaspoon hazelnut extract
• 1 3/4 cups granulated sugar
• 1 teaspoon baking powder
• 1 teaspoon baking soda
• 1 teaspoon fine-grain sea salt
• 1 cup peeled, toasted and finely chopped or ground hazelnuts
• 3 sticks (24 tablespoons) unsalted butter, at room temperature
• 1 cup sour cream, at room temperature
• 4 tablespoons unsalted butter, at room temperature
• 4 tablespoons all-purpose flour
• 1 cup granulated sugar
• 1 cup heavy whipping cream
• 1 cup peeled, toasted and finely chopped hazelnuts
• 1/4 teaspoon fine-grain sea salt
• 1 tablespoon hazelnut-flavored liqueur (recommended: Frangelico)
• 2 tablespoons finely chopped bittersweet chocolate or chocolate disks
• 8 ounces bittersweet chocolate, finely chopped or chocolate disks
• 1 cup egg whites, at room temperature (from 7 to 8 large eggs)
• 4 sticks (32 tablespoons) unsalted butter, at room temperature
• 2 cups peeled, toasted and finely chopped hazelnuts
• 8 whole peeled, toasted hazelnuts
• 8 milk chocolate curls