Heat the fat. Sweat flour in it. Deglaze with milk and boil up while stirring. Add bay leaf if necessary and simmer for about 10 minutes. Season to taste with salt and cayenne pepper
Cook the tortellini in plenty of boiling salted water for 10 minutes. Drain and let drain well
Clean, wash and slice the mushrooms. Peel and finely chop the onion. Heat the oil. Sauté mushrooms and onion. Season with salt and pepper, take out
Cut the ham into cubes. Fill into a flat greased casserole dish (approx. 20 x 30 cm) with tortellini, mushrooms, peas and sauce. Grate cheese over it. Bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C / gas: level 2) for approx. 1 hour