Ripe frozen bananas
Cocoa or hot chocolate mix
Once bananas have ripened peel them and place them in the freezer in a sealed container for at least a couple hours.
Combine frozen bananas, peanut butter, cocoa/hot chocolate mix, and chocolate milk in a smoothie maker (or if you don't have one a blender or food processor would also do the job). I generally follow the measurements of 1 and a half bananas, 2 tablespoons of peanut butter, 1/3 packet hot chocolate mix, and about 1/4 -1/2 cup chocolate milk. However, feel free to play around with the proportions of the ingredients based on how chocolate-y or banana-y or peanut butter-y you'd like your soft serve.