Elvis Cake

1 (18.25 ounce) box yellow cake mix
1/2 cup vegetable oil
1 small box instant vanilla pudding
4 eggs
1 cup sour cream
1/2 cup water
2 teaspoons cinnamon

Mix all ingredients except cinnamon in a large mixing bowl and beat for 10 minutes. Pour 1/2 of the mixture into a large tube pan and sprinkle with the 2 teaspoons cinnamon. Pour in remainder of batter. Bake for 1 hour at 350 degrees F.

Topping:
6 ounces chocolate chips
1/2 cup granulated sugar
2 tablespoons butter

Melt ingredients in a double boiler, then drizzle over the cake. If topping is too thick, add about 2 tablespoons of water.