Makes 20-24 cupcakes

2 1/4 cups all-purpose flour
1/2 cup unsweetened cocoa powder, sifted
1 1/2 teaspoons baking soda
3/4 cup coffee, at room temperature
3/4 cup Kahlua
3 large eggs, separated and at room temperature
3/4 cup granulated sugar
1/2 cup (1 stick) unsalted butter, at room temperature
1 cup packed light brown sugar

Kahlua Buttercream
6 tablespoons unsalted butter, at room temperature
3 cups confectioners' sugar, sifted
3 tablespoons unsweetened cocoa powder, sifted
4 tablespoons Kahlua
2 tablespoons coffee, at room temperature

Bailey’s Buttercream
1/2 cup (1 stick) unsalted butter, at room temperature
3 cups confectioners' sugar, sifted
2 teaspoons vanilla extract
4 tablespoons Bailey’s Irish Cream