1. Preheat the oven to 350°F. Grease and line two 9 inch round cake pans.

2. In a large bowl, whisk together the flour, sugar, cocoa powder, baking soda, baking powder, and salt.

3. Add the eggs, buttermilk, vegetable oil, and vanilla extract. Mix until smooth.

4. Slowly stir in the hot coffee or hot water until the batter is fully combined. The batter will be thin.

5. Divide the batter evenly between the prepared pans.

6. Bake for 28 to 32 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs.

7. Let the cakes cool in the pans for 10 minutes, then turn them out onto a wire rack and cool completely.

8. To make the frosting, beat the softened butter until creamy.

9. Add the cocoa powder and powdered sugar gradually, mixing well after each addition.

10. Pour in the heavy cream or milk and vanilla extract, then beat until the frosting is fluffy and spreadable.

11. Place one cake layer on a serving plate and spread frosting over the top.

12. Add the second cake layer and frost the top and sides.

13. Slice and serve once the frosting is set slightly.