For the Streusel

1. Combine all dry ingredients in a medium-sized bowl.
2. In a separate bowl, melt butter. Pour melted butter over dry ingredients. Use a pastry cutter or fork to blend butter into dry ingredients to create a crumbly mixture. Set aside.

For the Cupcake

1. Preheat oven to 350°F.
2. Combine vanilla cupcake mix with vanilla pudding. Add eggs, one at a time, beating well after each egg is added to ensure it is well mixed.
3. Add milk, oil, sour cream, and vanilla. Beat on medium speed until all ingredients are well combined. Use a spatula to scrape down the side of the bowl and turn the batter over from the bottom.
4. Line a cupcake pan with paper liners. Pour 1 heaping teaspoon of streusel in the bottom of each liner. Spoon about 3 tablespoons of cupcake batter into each liner on top of streusel. Each liner will be about ¾ full.
5. Bake at 350°F for 15-18 minutes until cupcakes are done. You do not want to top to turn brown. Check for doneness by inserting a toothpick in the middle of the cupcake. If the toothpick comes out clean, your cupcakes are done. Allow to cool completely.

For the Topping

1. Combine sugar and cinnamon in a shallow bowl or paper plate.
2. Melt butter in the microwave. Brush each cupcake with a thin layer of butter and roll in the cinnamon sugar mix.

For the Frosting

1. Allow butter to come to room temperature so it is soft but not melted. Beat butter in a mixer on medium speed until smooth and creamy.
2. Add brown sugar and mix until combined.
3. Slowly add powdered sugar 1 cup at a time while continuing to beat on medium speed. Add cinnamon and mix into the frosting.
4. Add vanilla and heavy whipping cream last and increase mixer speed to high to whip frosting until smooth and creamy.
5. Frost cooled cupcakes.