1 box yellow cake mix
4 eggs
1 cup sour cream
3/4 cup vegetable oil
1 cup butter, softened
1 cup brown sugar
2 T. flour
1 T. ground cinnamon
2 C. powered sugar
5 T. milk
1 tsp. vanilla extract
Preheat oven 350; spray baking dish with cooking spray.
In a mixing bowl, combine cake mix, eggs, sour cream, and oil; beat as directed on cake mix box. Spread batter in prepared pan and set aside.
In a small bowl, beat together butter, brown sugar, flour and Cinnamon until smooth and creamy. Drop cinnamon filling onto cake batter by spoonfuls. Drag a knife through batter and filling until swirled together. Bake 33-40 minutes or until cake tests done. Cool 15 minutes.
With a fork or wooden spoon handle poke holes in warm cake.
In a spouted bowl, whisk together powered sugar, milk and vanilla until smooth. Drizzle over cake allowing holes to fill . Serve warm or at room temperature.