It's Grandparents' Day on Sesame Street! Everyone is coming together to celebrate with a cookout. Gabrielle and her Grandma Nell are making their family's world-famous Grandpa ZZ's Triple Cheesy Macareenie. While Elmo, Tamir and Gabrielle help Grandma Nell prepare the dish, Grandma Nell tells them the story of how her Grandpa ZZ's dish all started. Grandpa ZZ wanted to make macaroni and cheese to share with the family, but he didn't have enough cheese! He found three small pieces of cheese and mixed them with butter, and milk and created the Triple Cheesy Macareenie. The best part about making it is being able to cook it together as a family. Just like how Grandma Nell made it with her grandpa, Gabrielle and Tamir get to make it with Grandma Nell every year for Grandparents' Day.