Step 1

Preheat oven to 350 degrees F. Coat a 9- x 13-inch baking dish with cooking spray.

Step 2

In a large bowl, combine cake mix, pudding mix, milk, and sour cream; beat 1 to 2 minutes, or until well blended. Pour batter into baking dish.

Step 3

Bake 30 to 35 minutes, or until toothpick inserted in center comes out clean. Cool in pan on wire rack.

Step 4

Evenly frost top of cake; cut into squares and serve.