Cake
Nonstick spray
2 cups cake flour
1 1/2 teaspoons baking powder
1/4 teaspoon baking soda
1/4 teaspoon salt
3/4 cup (1 1/2 sticks) unsalted butter, at room temperature
1 1/4 cups sugar
3 large eggs
3/4 cup buttermilk
1/4 cup Frangelico
1/2 cup roasted, skinned, and finely chopped hazelnuts (roasted in a 350-degree oven for 6 minutes, then chopped; roasted-hazelnut flour can be substituted)

Praline Buttercream
1 1/4 cups sugar
4 large egg whites
Pinch of salt
1/4 teaspoon cream of tartar
3/4 pound (3 sticks) unsalted butter, at room temperature
1/4 cup praline paste or filbert paste (available from New York Cake & Baking Distributor)
3/4 cup roasted, skinned, and coarsely chopped hazelnuts