An apparatus for roasting coffee beans comprises a roasting chamber for containing coffee beans. The roasting chamber is positioned within a resonant cavity of a waveguide. A microwave emitter produces microwave energy within the waveguide with one or more stable high intensity microwave regions within the roasting chamber to heat the coffee beans in the roasting chamber to a temperature sufficient to roast the coffee beans. A device configured to move the coffee beans within the one or more high intensity microwave regions is coupled to the roasting chamber.