1 yellow cake mix
2/3 c. oil
8 oz. sour cream
4 eggs
1 tbsp. cinnamon
1 c. brown sugar
2 1/2 c. powdered sugar
1/2 c. milk
1 tsp. vanilla

Combine together cake mix, sour cream, oil and eggs; mix well. Pour 1/2 of batter into a slightly greased 9 x 13-inch pan. Mix cinnamon and brown sugar; sprinkle over batter. Pour remaining batter over sugar mixture.

Bake 35-40 minutes at 350°F. Mix powdered sugar, milk and vanilla while cake is baking. As soon as cake is removed from oven, punch holes all over cake with a fork and pour icing mixture over the hot cake.