Prosperity sandwich is a traditional sandwich originating from St. Louis. Invented at the Mayfair Hotel in the 1920s, the sandwich consists of three slices of buttered toasted bread topped with a slice of ham and a slice of turkey. The sandwiches are sliced in half diagonally, and each serving consists of three halves that are arranged on a plate.

They're topped with tomato slices and a sauce consisting of butter, flour, milk, paprika, Worcestershire sauce, Swiss cheese, and Parmesan cheese. The sandwiches are browned under a broiler and served hot. If desired, add sautéed mushrooms and shallots before placing a layer of ham on the bread.