1 pkg. yellow cake mix
1 c. sour cream
4 eggs
1/3 c. oil
1 c. brown sugar, packed
3 tsp. cinnamon

Combine first 4 ingredients in bowl, mixing well. Pour into greased and floured 9 x 13-inch baking pan. Mix brown sugar and cinnamon in bowl. Sprinkle over batter. Swirl batter with knife. Bake using cake mix directions.

ICING:

2 c. powdered sugar
3 to 4 tbsp. milk

Combine ingredients in small bowl. Drizzle over warm cake.