Mix together the beef mince, onion, herbs and 1 cup of the bolognese sauce. Cook the pasta shells in boiling salted water for 5 minutes only and drain well. They will be undercooked at this stage.
Mix the remaining bolognese sauce with the beef stock or water and pour over the base of a large lasagne-style baking dish.
Place the half cooked pasta shells into the dish and fill with an equal amount of mince mixture. Sprinkle the cheeses over.
Bake at 180°C for 35-40 minutes until hot and golden and the meat is cooked. Serve with vegetables or a salad.