Cream of Watermelon Soup

I used to work in a brunch restaurant and when this soup was served, it always sold out very quickly. It is light and refreshing and perfect at a baby or bridal shower or even a ladies' luncheon. The restaurant owner shared the recipe with me, but I lost it without ever having made it. After much experimentation, I finally came up with a version that I liked and have been making it now for several years when fresh watermelon is in season. It isn't quite the same, but I still liked it enough to share. I like to serve with this chicken salad sandwiches. Cook time is for chilling overnight. Makes one blender full of soup.