Abstract: A grill overlay unit makes it possible to use a gas barbeque as a baking oven for baking such items as a pizza. The unit includes a flame resistant metal plate for placing over a barbeque grill, the plate having a series of louvered openings which allow heat to rise from the barbeque flames while blocking the flames. A support is provided for a baking pan a spaced distance, e.g. about 2 to 6 inches, above the louvered plate to provide a zone of uniform heating in the space between the louvered plate and the baking pan. This heating zone is preferably enclosed by side walls extending upwardly from the periphery of the louvered plate, with the top edge of the side walls serving as a support for a baking pan. With this arrangement, a food item such as a pizza may be perfectly baked under controlled, uniform heat within a backyard barbeque.