This is a beautiful, refreshing and healthful dessert! I chose a combination of frozen açaí berry puree and blueberries for a big boost of antioxidants. Most grocery stores carry açaí berry smoothie packs in the frozen section. I find mine at Whole Foods Market, Sprouts, or Costco. There is a little preparation for this recipe: you will need to freeze watermelon and prepare a white chocolate simple syrup ahead of time.