In a blender, add the frozen banana slices, 1/2 cup blueberry sauce and ½ cup coconut milk in your blender. Start on low and gradually increase speed. Depending on your blender, you might need to add more coconut milk, just a little at a time until the consistency looks like a frozen yogurt.
Once blended, scoop mixture and spread evenly intoa loaf pan or a glass dish and freeze.
Mix once an hour with large spoon for a couple of hours. If it freezes solid, remove from freezer, and let sit 15 minutes at room temperature before scooping.
Serve immediately and top with extra blueberry syrup.