01 - Peel the bananas and cut them into 1-inch rounds. Arrange the slices in a single layer on a parchment-lined baking sheet.
02 - Place the baking sheet in the freezer for at least 2 hours, or until the banana slices are completely solid throughout.
03 - Transfer the frozen banana slices to a high-speed blender or food processor. Blend until the mixture becomes creamy and smooth, stopping occasionally to scrape down the sides. Add vanilla extract, cocoa powder, or nut butter at this stage if desired, then blend again to incorporate.
04 - Serve immediately for a soft-serve consistency, or transfer to a freezer-safe container and freeze for 1 to 2 hours for a scoopable, firmer texture.
05 - Garnish with fresh berries, chopped nuts, or dark chocolate chips as desired and enjoy immediately.