Vanilla Cake with Tiramisu Buttercream and Bittersweet Ganache Filling

INGREDIENTS

• Cake:
• 3 3/4 cups cake flour
• 2 1/2 cups sugar
• 1 tablespoon plus 2 3/4 teaspoons baking powder
• 1/2 teaspoon salt
• 2 1/2 sticks (10 ounces) unsalted butter, at room temperature
• 1 1/4 cups plus 1/3 cup buttermilk
• 5 whole eggs
• 2 egg yolks
• 2 1/2 teaspoons vanilla extract
• Buttercream: (halve this recipe if you will be covering the cake with fondant)
• 6 large egg whites
• 1 1/2 cups sugar
• 1 teaspoon pure vanilla extract
• 1 1/4 pounds (5 sticks) unsalted butter, softened
• 2 tablespoons warm water
• 1 tablespoon instant coffee
• Ganache:
• 1/3 cup heavy cream
• 3 ounces bittersweet chocolate, chopped