Place the frozen banana slices into the bowl of a high-speed blender or food processor.
Add the cocoa powder, maple syrup, vanilla extract, and sea salt.
Pulse the mixture 5 to 10 times to break the frozen bananas into small, uniform crumbles.
Process on high speed for 1 to 2 minutes, stopping to scrape down the sides of the bowl with a silicone spatula as needed.
If the mixture is too thick to blend, add almond milk one tablespoon at a time until a smooth, soft-serve consistency is achieved.
Serve immediately for soft-serve texture, or transfer to an airtight container and freeze for 1 to 2 hours for a firmer, scoopable consistency.