Preheat oven to 425°F (220°C). Line a baking sheet with parchment or foil.
Toss cauliflower with olive oil, Old Bay, chili pepper, and black pepper.
Spread evenly on baking sheet. Roast for 25–30 minutes, flipping halfway.
Sprinkle cheddar and parmesan on top. Roast 5 more minutes until cheese is melted and bubbly.
Serve hot for best crispiness.
