1- In a pot of boiling salted water, cook the cauliflower bouquets for 8 minutes.
2- Drain and set aside.
3- Preheat the oven to 375F.
4- Prepare the Béchamel sauce: in a saucepan, melt the butter. Add the flour and mix. Add the warm milk slowly, stirring. Mix until you get a smooth sauce. Add the nutmeg. Season with salt and pepper.
5- In a buttered baking dish, arrange the cauliflower bouquets.
6- Cover with Béchamel sauce and grated cheese.
7- Bake at 350F for 8 minutes or until the cheese is melted and golden brown.
8- Serve immediately.