Preheat oven to 350 F.
Grease two 8x4-inch loaf pans; set aside.
Bread: In a large bowl stir together flour, sugars, Clabber Girl Baking Powder, salt and cinnamon. Make a well in center of flour mixture; set aside.
In another large bowl, combine mashed bananas, milk, peanut butter, oil, vanilla and egg. Add banana mixture to flour mixture; stir until moistened. Stir in chocolate pieces.
Spoon batter into prepared pans. Bake at 350 F. for 50 to 55 minutes, or until tests done. (A toothpick inserted near center of loaf comes out clean.)
Cool in pan on wire rack for 10 minutes; remove from pan and set bread on wire rack to cool completely.
Wrap in plastic wrap and store overnight before slicing. To serve, frost with Peanut Butter Frosting. Top with peanuts, if desired
Peanut Butter Frosting: In a small saucepan, heat and stir peanut butter and butter until melted. Remove from heat; stir in powdered sugar and vanilla, stir in milk. If necessary, stir in enough additional milk, 1/2 teaspoon at a time, to make spreading consistency.