Make a bechamel sauce using 80 g/3 oz (6 tbsp) butter, the flour and the milk.
Stir in the tomato sauce.
Check for seasoning and add salt and freshly ground pepper if needed.
Cook the pasta for half the time given in the packet directions, drain and mix well with the sauce and half the freshly grated cheese.
Turn into a buttered oven dish and cover with the rest of the grated cheese mixed with the breadcrumbs.
Dot with the remaining butter.
Bake in a hot oven for 10 minutes.
If a browner crust is desired, place under a hot gnll (broiler) for a few minutes.