Cupcakes: For the cupcakes, cream together the butter, white bean puree (or more butter), sugars and eggs until smooth and creamy. Add the sour cream, vanilla, salt and ripe bananas and beat until smooth. Add the baking powder, soda and flour until mixed thoroughly (don't over mix). Pour batter into the cupcake tins that have been well greased. Bake at 350 for 15-18 minutes, or until center is cooked through. Remove from oven and let cool, and then frost.
For the frosting: melt in a microwave safe bowl, the brown sugar and butter for 30 seconds. Stir the mixture and the microwave for 30 seconds more. Stir again and add 8 ounces of cream cheese. With an electric mixer, whip together these ingredients until the mixture is soft, fluffy and white. Add the salt, cinnamon and powdered sugar. Continue to whip until the frosting is light and airy. When cupcakes are cooled, frost the top of the cupcakes with this delicious frosting. Garnish with flecks of cinnamon if you wish.