How to make
Preheat the oven to 390°F (200 degrees).
Boil the broccoli in boiling salted water until they're almost cooked, but still slightly crunchy.
Make a white sauce by melting the butter and lightly frying the flour.
Add the milk and boil the mixture. Boil it until it thickens. Remove it from the heat and add the heavy cream, nutmeg, salt and black pepper.
Pour half of the grated yellow cheese in the sauce.
Pour the broccoli and dairy sauce in a baking pan, sprinkle them with the remaining cheese and bake the casserole until it's done - about 15 minutes.