Preheat oven 350°

Mix well in a large bowl - cake mix, oil, eggs, sour cream

Mix seprately- brown sugar and cinnamon

Pour 1/2 of the cake batter in a greased 9 ×13 cake pan

Add all brown sugar mixture in a layer and top with remaining cake batter.

Bake for 30 - 40 minutes

For the icing mix - powered sugar, milk, and vanilla

After removing cake from the oven apply icing while still warm.

Let cool on the kitchen counter - cut, serve, and enjoy