Butter, for greasing the pans
1 3/4 cups all-purpose flour, plus more for pans
2 cups sugar
3/4 cups good cocoa powder
2 teaspoons baking soda
1 teaspoon baking powder
1 teaspoon kosher salt
1 cup buttermilk, shaken
1/2 cup vegetable oil
2 extra-large eggs, at room temperature
1 teaspoon pure vanilla extract
1 cup freshly brewed hot coffee
Chocolate Buttercream Frosting, recipe follows

Chocolate Frosting:
6 ounces good semisweet chocolate (recommended: Callebaut)
1/2 pound (2 sticks) unsalted butter, at room temperature
1 extra-large egg yolk, at room temperature
1 teaspoon pure vanilla extract
1 1/4 cups sifted confectioners' sugar
1 tablespoon instant coffee powder