Chocolate Ganache Frosting:
For the cupcakes: Preheat oven to 350 degrees F with rack in the center of the oven. Line regular 12 cup muffin pan with paper cups
In one large mixing bowl, whisk together the sugar, flour, cocoa powder, baking powder, baking soda, and salt.
In another large mixing bowl, gently whisk together the eggs, mashed bananas, milk,water, oil, and vanilla extract. Add the wet mixture to the dry ingredients and stir until just combined. Pour (or use an icecream scoop to scoop) the batter into the cups, about 3/4 full. Bake for 20-25 minutes (until a toothpick inserted in the center of a cupcake comes out clean.) Remove from oven and let them cool on a wire rack. Frost with the Ganache once the cupcakes are completely cool.
For the ganache: Put the chocolate pieces, or chips in a medium-sized heatproof mixing bowl (use glass or stainless steel) and set aside. In a small saucepan, heat the cream and butter over medium heat. Bring cream just to a boil and immediately remove from heat and pour the boiling cream over the chocolate. Allow the chocolate and hot cream to stand for 5 minutes before stirring until combined and smooth (this takes a few minutes).
Let the smooth ganache cool completely, and then beat until firm and shiny. (This takes about 10 minutes of heavy beating and the ganache frosting will still be pretty shiny but should hold itself stiff.) Pipe with a small star tip onto the completely cooled cupcakes, or with an offset spatula or knife, spread the frosting on top of each cupcake.
Optional additions: Dust with powdered sugar; add a fresh raspberry;or sliced strawberries to the top of each frosted cupcake.