Step 1

Preheat oven to 350 degrees F.

Step 2

Pour cake mix, pudding mix, eggs, water, oil and buttermilk in a mixing bowl. Mix until combined.

Step 3

Spray a 9 x 13 in pan with non-stick spray. Spread batter in pan. Bake for approximately 20- 25 minutes or until toothpick comes out clean.

Step 4

Add butter, cocoa powder and milk to small saucepan. Cook over medium heat until it just starts to boil. Remove from heat.

Step 5

Add powdered sugar into mixing bowl. Add in vanilla extract and then pour chocolate mixture over powdered sugar. Mix until creamy. Spread over cake.