Chop the bananas into 1-inch (2.5 cm) slices and add them to a freezer-safe container (with space in between). Freeze them until solid (at least 1 hour). If you freeze them overnight, let them thaw for about 20 minutes before using.
Add the frozen banana pieces, nut/seed butter, and maple syrup (if used) to a high-speed blender. Blend until