1. Preheat oven to 350 degrees and line pans with cupcakes liners.
2. Sift cake mix into a large bowl.
3. Add bananas, eggs, oil, sour cream and vanilla extract and stir until well combined.
4. Fold in blueberries.
5. Fill cupcake liners 3/4 full and bake for 15-20 minutes or until an inserted knife comes out clean.
6. Let cool.
7. Cream Cheese Frosting: Beat butter and cream cheese until smooth. Add vanilla extract, milk and 2 C. powdered sugar and beat again. Slowly add in more powdered sugar until you reach your desired consistency.
8. Pipe onto cool cupcakes and top with fresh berries!