Ingredients:

1 yellow cake mix 

1 cup brown sugar

2 cups powdered sugar

3/4 cup oil

1 Tablespoon cinnamon

4 Tablespoons milk

4 eggs

1 Tablespoon vanilla extract

8 oz sour cream

Instructions:

Mix cake mix, oil, eggs, and sour cream by hand, about 50 strokes.

Put half the batter in 9 x 13 pan.

Combine brown sugar and cinnamon and spread over entire cake. Spread the rest of the batter on top of this.

Use a knife to make swirls in the cake.

Bake at 325 degrees for about 40 minutes.

Blend powdered sugar, milk and vanilla extract and spread on warm cake.