Cake:
2 1/4 cup all-purpose flour
2 1/4 cup white granulated sugar
1 cup cocoa powder
1 tablespoon instant espresso
2 teaspoons baking soda
1 1/2 teaspoons baking powder
1 1/2 teaspoons salt
3 large eggs
1 cup buttermilk
1 cup warm water
2 tablespoons olive oil
2 teaspoons vanilla extract

Fudge-y Chocolate Frosting:
1 1/2 cups unsalted butter, at room temperature
4 cups powdered sugar, sifted
6 ounces dark chocolate or semi-sweet chocolate chips, melted
2 tablespoons sour cream or buttermilk or cream
1 teaspoon vanilla extract