Abstract: A modular radiant heating unit adapted for installation into a cooktop or the like. In one embodiment, the heating unit comprises an open-topped pan having a bottom and circumferential sidewall defining a flanged upper rim. A thermally insulating support element disposed in the bottom of the pan, and a radiant heating element is disposed in a pattern on the support element. An insulation ring is extends around and adjacent to the inner surface of the circumferential sidewall of the pan. A thermally insulating washer-like gasket is disposed atop the insulation ring and the flanged upper rim of the pan. A glass-ceramic cover plate is disposed atop the gasket, such that the gasket enhances the seal between the plate and the pan. The present invention also includes methods of assembling a modular radiant heating unit having such a gasket.