Bumpy Cake

Steps

1. Preheat oven to 350°F (175°C) and grease a 9x13-inch pan.
2. Whisk together flour, baking soda, salt, and cocoa powder in a medium bowl.
3. In a large bowl, beat butter and sugar until light and fluffy, about 3-4 minutes.
4. Beat in eggs one at a time, then mix in vanilla.
5. Alternately mix in the dry ingredients and buttermilk, starting and ending with the dry mixture.
6. Stir in hot water until batter is smooth (it will be thin).
7. Pour batter into the prepared pan and bake 30-35 minutes, until a toothpick comes out clean.
8. Let cake cool completely in the pan.
9. Make the buttercream: beat butter and shortening until smooth, then gradually beat in powdered sugar.
10. Mix in vanilla, salt, and enough cream to form a thick, pipeable frosting.
11. Transfer frosting to a piping bag with a large round tip and pipe even rows of bumps across the cooled cake, spacing rows about 1 inch apart.
12. Chill the cake for 30 minutes.
13. Make the fudge icing: combine cream, sugar, butter, cocoa powder, and salt in a saucepan over medium heat.
14. Stir until mixture boils gently and thickens slightly, about 4-5 minutes, then remove from heat and stir in vanilla.
15. Let icing cool slightly until pourable but not hot enough to melt the buttercream.
16. Pour icing evenly over the cake, tipping the pan gently to coat the bumps without spreading them.
17. Chill until icing is set, then slice and serve.