Place bananas, almond milk, and mint leaves into a high-power blender (I used my blendtec , but you could use a food processor, too).
Blend until smooth. Fold in dark chocolate and eat immediately like a soft serve. You could also place it in a freezer-safe container and freeze for 2-3 hours, then scoop and serve.
Notes
You can add more or less almond milk to change the consistency. You could also add more or less mint leaves to change the taste, too.