Line 24 muffin cups with paper cups. In medium bowl, stir together flour, baking powder, salt, and baking soda. In a small bowl, combine mashed banana, milk, sour cream and vanilla.
Preheat oven to 350. In large bowl, beat butter. Gradually add sugar, about 1/4 cup at a time, beating on medium speed until light and fluffy. Add eggs, one at a time, beating well after each addition. Alternately add flour mixture and banana mixture to the butter mixture, beating on low speead after each addition just until combined.
Spoon batter into prepared muffin cups, filling each one 1/2 to 2/3 full. Use the back of a spoon to smooth out the batter.
Bake 18 - 20 minutes or until a toothpick inserted in comes out clean. Cool cupcakes in muffin cups on wire racks for 5 minutes. Remove cupcakes from tins and cool completely on wire racks.
Just before serving, pipe whipped topping into the center of the cupcake.
Top each cupcake with a small coop of ice cream. Drizzle with chocolate sauce. Pipe some of the remaining whipped cream on top of ice cream. Top with cherry and/or nuts.
Option 2: If you do not have ice cream or if the use of ice cream is not practical (i.e. potluck), frost the cupcake with milk chocolate frosting and top with chopped nuts. LINK NOTED BELOW.