An improved apparatus and method for heating food products by forced air convection are disclosed. The apparatus comprises a tunnel heater having a tunnel-like cavity through which food products to be heated are conveyed. Air is drawn from within the tunnel cavity by a circulating blower arrangement, with air flow directed against the food products through upper and lower foraminous plates disposed above and below and adjacent to the tunnel cavity. Aerodynamically efficient ducting of the circulating air is provided by scroll-shaped passages positioned in association with the blower arrangement, and venturi-like passages positioned upstream of the foraminous upper and lower plates. A conveyor is provided for automatically advancing food products through the tunnel cavity, with heating of the food products taking place in an efficient and readily controlled manner.