You can reduce the sugar if your melon is super sweet or if you have a simple syrup use that instead of sugar. When frozen, scoop the granita out with a warm spoon, put in a pretty glass and sprinkle with fresh berries or lime zest, make a sno-cone for your kids or for a grown up version add a splash of Vodka or Seltzer, and sip away....
4 cups seedless watermelon chunks
1/2 cup sugar
Juice of 2 limes or about 1/4 to 1/2 cup
Combine all ingredients in a food processor. Puree until smooth. Pour into a shallow, wide pan covering with a lid or saran wrap. At the two or three hour mark take it out of the freezer and scrape with a fork or large spoon. Repeat process two more times. Store covered in the freezer until your ready to scrape away the heat with something cool to eat.