Heat the oven and prep a pan. Set the oven to 425°F (220°C). Line a baking sheet with parchment for easy cleanup.
Roast the cauliflower. Toss florets with olive oil, salt, and pepper.
Spread on the sheet and roast 18–22 minutes, until tender with browned edges.
Cook the pasta. Boil in salted water until just shy of al dente (about 1 minute less than package time). Drain and set aside.
Warm the buffalo mixture. In a small saucepan or bowl, melt 1 tablespoon butter and whisk with 1/3 to 1/2 cup hot sauce. Start with less for milder heat.
Set aside.
Make the roux. In a large pot over medium heat, melt 4 tablespoons butter. Whisk in flour and cook 1–2 minutes until foamy and lightly golden.
Build the cheese sauce. Slowly whisk in milk, stirring until smooth. Simmer 3–4 minutes to thicken.
Off the heat, stir in cheddar, Jack, and cream cheese (if using) until melted. Season with garlic powder, onion powder, paprika, salt, and pepper.
Add the buffalo kick. Whisk the buffalo mixture into the cheese sauce. Taste and adjust salt or heat.
The sauce should be creamy, tangy, and lightly spicy.
Combine. Fold in pasta and roasted cauliflower until coated. If it looks too thick, splash in a bit more milk to loosen.
Optional: Broil for a golden top. Transfer to a greased baking dish, sprinkle with extra cheese or breadcrumbs, and broil 2–4 minutes until bubbling and browned.
Finish and serve. Top with green onions, parsley, or blue cheese crumbles. Serve hot.