Preheat oven to 350 degrees.
In a large mixing bowl, combine flour, sugar, baking powder, salt, oil, chocolate milk, bananas & egg.
Mix by hand or with an electric mixer until fully combined.
Stir in chocolate chunks.
Pour batter into greased & floured bread pan, or divide among three smaller bread pans.
Bake at 350 degrees until bread is golden brown and center is set - approx. 60 minutes for 1 loaf or approx. 45 minutes for 3 smaller loaves.
Remove from oven and place pan(s) on a cooling rack for 15 minutes.
Loosen edges from pan; carefully remove bread and place on a cooling rack to cool completely.
Prepare drizzle by combining powdered sugar, marshmallow fluff, and 1 Tbsp. milk. Stir to a drizzling consistency; drizzle generously over cooled bread.