National Green Bean Casserole Day is observed annually on December 3 in the United States. This day celebrates the iconic green bean casserole, a popular side dish during Thanksgiving and Christmas dinners. The dish, which consists of green beans, cream of mushroom soup, and crispy fried onions, was invented in 1955 by Dorcas Reilly, a recipe developer for the Campbell Soup Company. Originally called "green bean bake," it gained popularity in the 1960s when Campbell's began printing the recipe on their soup cans. On this day, people often take the opportunity to perfect their green bean casserole recipes, experimenting with variations that may include fresh mushrooms, sautéed onions, or additional ingredients like bacon or cheese. National Green Bean Casserole Day was created by Jace Shoemaker-Galloway, who aimed to honor this beloved dish that has become a staple at holiday gatherings.