An insulated cover and method that makes it possible to create a thermal environment on a home gas or charcoal grill similar to that produced by a wood fired brick oven or commercial pizza oven. The cover is made from a high temperature resistant, thermal insulation material that is encapsulated (sandwiched) between thin metal sheet or metal foil skins. The insulated cover covers both a food support surface that has been placed on the grill's grate directly over the grill's heat source and the remainder of grills grate area that is suspended directly above the grills heat source that is not already covered by the food support surface. The food items are cooked from below by the thermal energy stored in the food support surface, and from above by the thermal energy contained within the low volume zone created by the insulated cover resulting in uniform, fast, even and energy efficient cooking of food items like pizza.