1 package yellow cake mix
3/4 cup vegetable oil
1 (8 ounce) container sour cream
1 cup brown sugar, firmly packed
1 tablespoon ground cinnamon
2 cups powdered sugar
4 tablespoons milk
1 tablespoon pure vanilla extract
In a large mixing bowl, combine cake mix, oil, eggs and sour cream. Stir by hand approximately 50 strokes, or until most large lumps are gone.
Pour half of the batter into an ungreased 9x13 inch glass baking dish.
Combine the brown sugar and cinnamon; sprinkle the mixture over the batter in the cake pan.
Spoon the other half of the batter into the cake pan, covering the brown sugar and cinnamon.
Drag a knife through the cake batter in swirling motions, making a design that looks like a honey bun (or whatever design you want to make).
Bake in a 325 degree oven for 40 minutes, or until a toothpick inserted into the center of the cake comes out clean.
In a small bowl, whisk together the powdered sugar, milk and vanilla until smooth. Frost cake while it is still fairly hot.