In a mixing bowl, combine dry cake mix, sour cream, eggs and oil; beat well.
Spread half of the batter into a greased 13-in. x 9-in. x 2- in. baking pan.
Combine brown sugar and cinnamon; sprinkle over batter. Carefully spread remaining batter on top. bake at 350 degrees F for 30-35 minutes or until a toothpick inserted near the center comes out clean.· 35m
Combine icing ingredients and drizzle over warm cake.