*You can either cut the watermelon into 1-inch/2.5-cm cubes or scoop out the flesh using a melon baller. Arrange the watermelon in a single layer onto a parchment paper-lined baking sheet and freeze until firm, 4-5 hours. (I usually freeze mine overnight). The watermelon needs to be fully frozen; otherwise, it will become slushy as soon as you start blending it.
**Cut the bananas into 1-inch/2.5-cm thick slices. Arrange the slices in a single layer onto a parchment paper-lined baking sheet and freeze until firm, 3-4 hours.
***Prep time does not include freezing the fruit, about 5 hours.
****Nutrition information is approximate and may contain errors. Please, feel free to make your own calculations.