A resplendent portrait of the Amazing Grandmum
Grandmum (more formally Grandmother Mumford) is the grandmother of the Amazing Mumford. She is equally amazing, and is depicted and discussed in The Sesame Street Cookbook.
Grandmum considered chicken soup to be inherently magic, and that "a little chicken soup makes everything taste better." Mumford attempts to use her magic potion to improve his usual peanut butter sandwich lunch, and instead creates "A La Peanut Butter Soup."