Remove the frozen bananas from the freezer and allow to stand for about 10 minutes. The high speed blender might find it difficult to process bananas that are frozen solid.
In a high speed blender, blend all the ingredients on high until well mixed. I usually stop in the middle of blending and scrape the sides of the blender jug with a scraper to ensure the nut butter mixes well with the bananas, and then continue blending.
The ice cream is best enjoyed immediately, but can be stored in the freezer for later.
Enjoy!