Combine Cool Whip/cream cheese mixture and gelatin/sherbet mixture, blending until completely smooth. Since I’m using an immersion blender, I spoon the cream cheese and Cool Whip into the pan and blend, but putting both into a large high-powered blender will work, too. The goal is to get the entire mixture as smooth as possible with no lumps. My Grandma Bette just employed her hand-held mixture and a lot of patience, but do what works best for you.