"The Mystery of the Half-Slice: McDonald’s Filet-O-Fish Cheese Conundrum"

The McDonald’s Filet-O-Fish originally had no cheese when it was first developed by franchisee Lou Groen, but a half-slice was added after the sandwich outsold a proposed meatless option. McDonald’s maintains that the half-slice of cheese has been a constant since the sandwich hit the nationwide menu in 1965, citing it as the perfect balance for the tartar sauce and fish coating. Despite customer inquiries, McDonald’s has not provided additional information on the decision.