For the Cake:

• 2 cups all-purpose flour
• 3/4 cup unsweetened cocoa powder
• 1 1/2 teaspoons baking powder
• 1 1/2 teaspoons baking soda
• 1 teaspoon salt
• 2 cups granulated sugar
• 2 large eggs
• 1 cup buttermilk
• 1/2 cup vegetable oil
• 2 teaspoons vanilla extract
• 1 cup hot water or hot coffee

For the Chocolate Ganache Filling and Topping:

• 1 cup heavy cream
• 8 oz semisweet or dark chocolate, chopped
• 2 tablespoons unsalted butter

For the Chocolate Buttercream (optional for frosting sides):

• 1 cup unsalted butter, softened
• 3 cups powdered sugar
• 3/4 cup cocoa powder
• 1/4 cup heavy cream
• 1 teaspoon vanilla extract
• pinch of salt