First, put the macaroni in salted water to boil. In the meantime, wash the broccoli and cut them finely.
Fry the finely chopped onion and broccoli in hot oil, season with salt and pepper, then add the milk and leave on very low heat to boil once again.
Once the macaroni are cooked, drain them and put them in the oven dish in which you intend to bake.
Arrange some macaroni, a little of the mixture on top, macaroni again and mixture again. Sprinkle the top with plenty of grated cheese.
Bake in the oven for about 10 minutes, until everything catches a nice golden color.