Rinse the broccoli and cut into florets, approximately 1″ cubes. Peel the stalks and cut them into pieces as well. Put broccoli and chopped onion in a casserole dish, toss with olive oil and some salt and pepper. Roast broccoli for 20 minutes.
Meanwhile, melt the butter in a sauce pan and add the flour. Stir and cook 45 seconds until smooth and beginning to smell toasty.
Add half the milk and stir briskly to combine. Add the rest of the milk and seasonings.
Add ½ cup of the cheese and stir to melt.
Remove broccoli form over after cooked, and pour your cheesy sauce over the broccoli. Toss to coat.
Sprinkle some remaining cheese on top and return casserole dish to the oven for another 15-20 minutes.
Mmmmm, is there anything better than broccoli and cheese?!