Place the frozen banana slices and milk in the bowl of a food processor. Blend and pulse until just smooth, stopping to scrape down the sides with a rubber spatula occasionally. Don't over-blend.
Add the peanut butter, a pinch of salt, and optional sweetener to taste and pulse to combine. Stir in chocolate chips.
Enjoy immediately as a soft serve or transfer to a freezer container for later. Once frozen solid, let nice cream sit at room temperature for about 30 minutes to soften before eating.