Place the cantalope, lemon juice, and zest in a food processor and pulse until coarsely chopped. Add the mint and salt and pulse to combine. Transfer to a large bowl, cover, and chill for at least 30 minutes.
Place the cream and sugar in the bowl of food processor and process until slightly thickened. Add the basil and process until thick-about 20 seconds-and set aside. Add the grape to the soup right before serving. Divide evenly among four bowls and top with the cream. Enjoy!
You may use purple sparkling grape juice, but this will change the color of the soup.