A cooking appliance device includes a heating unit having a heating element for heating a cooking chamber in a heating operating state, and a cooking chamber element configured to at least partially bound the cooking chamber. The cooking chamber element has a part region with a surface shape which changes in the heating operating state in response to a thermal expansion of the cooking chamber element. The heating unit includes an adapting element which is arranged at least in part on the cooking chamber element and has in facing relation to the part region a surface which adapts in the heating operating state to the surface shape of the part region.