Preheat the oven to 325°F. Line the inside of a 6-inch round cake tin with parchment paper.
Add the bananas, eggs, vanilla extract, salt, sugar alternative, and fat-free cottage cheese to a blender. Blend until completely smooth.
Pour the batter into the prepared pan. Bake for 52–55 minutes, until the edges are set and the center is almost set but still slightly jiggly. The exact time may change with a different pan size or material.
Turn off the oven, open the door, and leave the cheesecake inside for 10–15 minutes.
Remove the cheesecake from the oven and let it finish cooling. Refrigerate for a few hours, until cold and set, before slicing into four servings.