1.
Heat the
extra-virgin olive oil in a saucepan. Add the flour and cook, stirring constantly. Add the warm milk and nutmeg and stir until the mixture forms a béchamel sauce with no lumps.
2.
Add the grated cheeses (except the mozzarella) and cook over low heat until they melt into the béchamel. Season to taste.
3.
Cook the penne following the manufacturer’s instructions.
4.
Transfer the penne into a baking pan, well buttered so it won’t stick. Add the cheese sauce and stir well. Sprinkle the mozzarella on top and brown under the broiler for a few minutes.