Scoop 2 cups each from the watermelon and the cantaloupe using a melon baller. Carve the remainder of the watermelon out and reserve shell.
Add to a blender the chopped mint, chopped basil, lemon juice, simple syrup and amaretto. Blend until smooth.
Add the watermelon and cantaloupe balls to the carved out watermelon half.
Add the vinaigrette to the balls and toss to combine.
Garnish with the mint and basil sprigs and taste.