Cook the tortellini in the vegetable stock according to the instructions on the packet, drain, collect the stock and keep the tortellini warm.
Cut the ham into fine strips and quarter the tomatoes. Melt margarine, stir in flour, fill up with milk and 250 ml of stock and deglaze. Melt the cheese in the sauce. Add the ham strips and season with salt, pepper and nutmeg.
Distribute the tortellini on the 4 plates, pour the sauce over them, garnish with basil and tomato.