Cut your watermelon into 1″ cubes and freeze in the freezer until frozen. You need 2 cups to make 2 drinks, so freeze some for now and some extra for later—I promise you’ll want another one soon.
Once your watermelon is frozen, add 2 cups to a blender and add in 1 cup of rosé.
Chop up 6 mint leaves and add to the blender (add more if you love mint and less if you don’t). I would finely chop your mint leaves first rather than just add them whole to the blender as you don’t actually blend the drink very much and you want to make sure the mint leaves are chopped and well dispersed.
Pulse your blender until all the ingredients are mixed together. Try not to blend more than you have to so you retain as much slush as you can without blending it into a total smooth juice. You want the slush to look fine and not too chunky.
Taste your frosé and add some simple syrup to taste if needed and pulse once or twice quickly to combine the syrup into the frosé. Pour into glasses and garnish with a mint leaf and wedge of watermelon and it’s ready to serve!