Place the potato pancakes on the grill over the fat pan of the oven without defrosting. Bake in the preheated oven (electric cooker: 200 °C/ gas: level 3) for approx. 10 minutes. Clean, wash and slice the tomatoes. Drain mozzarella, also in slices, cut ham into strips. Cover potato pancakes with tomatoes, ham and mozzarella. Season with thyme, salt and pepper and sprinkle with parmesan. Bake for another 10 minutes at the same temperature until golden brown