Blend the ingredients: Add the frozen bananas, frozen raspberries, watermelon cubes, and silken tofu to a high-speed blender. Blend until the mixture is completely smooth and creamy.
Freeze briefly: Pour the mixture into a shallow container or freezer-safe dish with a lid and place it in the freezer.
Serve: Freeze for about 2 hours, or until the ice cream has a soft-serve texture. Scoop into bowls and drizzle with your favorite liquid sweetener if desired.Tip: If the ice cream freezes solid, let it sit at room temperature for 5–10 minutes before scooping.