Cut the cauliflower in florets. Add in a boiling water to blanch for 5 minutes. Drain the water off then set aside.
Preheat the oven to 355°In a pot, melt butter. Whisk in flour to form the roux. Add milk. Stir a few times then add the shredded cheese. Season with sprinkles of garlic powder, salt, and pepper. Place the blanched cauliflower into a casserole dish. Stir in the cheese sauce.
Sprinkle the extra 1/4 cup of shredded cheese on top. Bake it in the oven for 20 to 25 minutes.