Cinnamon Swirl Cake

I have my mother-in-law to thank for this wonderful recipe. I didn't change a thing to it. It is one of the best cakes a person could possibly make! So delicious.

Cinnamon Swirl Cake
1 package of yellow cake mix
3.5 oz. instant vanilla pudding mix
1/2 cup soft margarine
1 cup sour cream
4 eggs
1 tsp. vanilla
1/2 cup brown sugar
1-1/2 tsp. cinnamon

1. Combine the cake mix, pudding mix, margarine, sour cream, eggs, and vanilla.
2. Beat for 10 minutes. This may seem like a long time, but it's necessary to get a nice fluffy cake.
3. Mix the brown sugar and cinnamon in a separate bowl.
4. Turn half of the batter in a greased bundt pan. Sprinkle 1/2 of the sugar mix on top of the batter. Add the remaining batter and top with the remaining sugar mix.
5. Swirl with a knife to create a swirl of the sugar and cinnamon into your cake.
6. Bake at 350 degrees for 50 minutes. Allow the cake to completely cool before slicing and serving.