Start by making a white sauce or “roux” by melting 1/2 cup butter in a saucepan and then add in 1/2 cup flour. Cook and stir for about a minute.
Then add in milk, pouring it slowly to avoid lumps, and keep stirring as it thickens. Once blended well, add in cheddar cheese, mushroom soup, salt, pepper, garlic and sugar – taste test as you go to see what it needs. If you get this cheese sauce right, the whole recipe will be delicious.
Remove from heat so it doesn't burn.
Meanwhile, get your broccoli cleaned and ready – I usually cut parts of the stems off.
Often I will also add in cauliflower and/or carrots, which I will lightly steam before assembling to bake, just until they are crisp-tender. Frozen broccoli doesn’t need to be steamed first because it gets done enough just in the oven – if it's fresh broccoli or if you like it really soft, you could steam it for a couple minutes; I like my carrots to still be just a smidge crunchy when they’re done, so I only steam them for a short time, too.
Butter a 8 1/2 x 11 glass baking dish. Place vegetables in the bottom and pour cheese sauce over the top. Bake 20-30 minutes at 350*. Meanwhile, melt 8 Tablespoons butter (or more if so desired!) and stir in about 1 1/2 cups bread crumbs or cracker crumbs. When the casserole has about 10-15 minutes left, sprinkle this on top and finish baking until crumbs are golden. Enjoy!
Recipe by Kelly the Kitchen Kop at https://kellythekitchenkop.com/broccoli-cheese-casserole-with-crumb-topping/