A cooktop appliance or heating element, as provided herein, may include a sensor support assembly positioned within a heating zone of the heating element. The sensor support assembly may include a shroud cover and a thermostat. The thermostat may be mounted to the shroud cover. The thermostat may include a base and a top cap held on the base. The top cap may be positioned above the shroud cover and spaced apart therefrom. A vertical air gap may be defined between the top cap and the shroud cover.