1 banana, chopped and frozen
1/2 to 1 tbsp vegan chocolate chips (most high quality dark chocolate is vegan, so if you can't find the chips then just chop up a small piece of a chocolate bar or some unsweetened bakers chocolate)
1 tbsp natural peanut butter (the kind that you have to stir)
1/2 tsp vanilla (optional)
agave or another liquid sweetener, to taste (optional)
1/2 tbsp raw shelled hemp seeds (optional)
Blend all the ingredients except the chocolate in a food processor or blender. Stir in the chocolate chips and serve.
Also, if you're impatient or don't have a working freezer (the one in my mini-fridge is incredibly small and doesn't work, and the communal freezer for our floor doesn't work either. It also smells horribly because of the non-veg stuff people put into it so I probably wouldn't use it anyway) then you could either put your banana in the fridge or just use it at room temperature to make more of a banana pudding. This is so delicious. I'm sure that it would be even better with some chopped walnuts. Feel free to use whatever nut butter you prefer. Peanut butter was just what I had on hand.
Gena at Choosing Raw also has a great banana soft-serve recipe, as does Averie at Love Veggies and Yoga (this one I've linked you to is for vegan mint chocolate chip soft serve. DOESN'T IT SOUND AMAZING?!)