Prepare cupcakes as directed on package, adding sour cream and 1 teaspoon cinnamon while adding the other ingredients.
Make Cinnamon Roll Filling by melting butter in pan. Combine with brown sugar and add 1 teaspoon cinnamon.
Put enough cupcake batter in each of the paper liners to cover the bottom. Add approximately 1/2 teaspoon of the Cinnamon Roll Filling to each cupcake.
Swirl with a toothpick.
Cover with batter until cupcake liners are at least 2/3 full.
Bake according to package instructions. Transfer to a wire rack to cool.
Make Frosting by creaming together butter and cream cheese. Add powdered sugar slowly, beating well after each addition. Stir in vanilla. Beat until light and fluffy.
Sprinkle cinnamon on top.
Serve and Enjoy!