A food preparation appliance includes a housing, a conveyor, a thermal element, a first sensor, a second sensor, and a third sensor. The housing defines an inlet, an outlet, and a processing zone between the inlet and the outlet. The conveyor is configured to move a food product from the inlet, through the processing zone, and to the outlet. The thermal element is positioned within the processing zone. The first sensor is positioned proximate the inlet of the housing and along a lateral side of the conveyor or along a first cantilever arm extending laterally across the conveyor. The second sensor is positioned within the processing zone. The third sensor is positioned proximate the outlet of the housing and along a lateral side of the conveyor or along a second cantilever arm extending laterally across the conveyor.