1. Preheat the oven to 425°F (220°C) and line a rimmed baking sheet with parchment paper.
2. Slice the cauliflower head into florets or 1/2-inch thick steaks, ensuring similar size for even cooking.
3. Place the cauliflower in a large bowl, drizzle with olive oil and melted butter (if using), then toss to coat evenly.
4. In a small bowl, mix garlic powder, salt, paprika, and black pepper, then sprinkle over the cauliflower and toss again to distribute seasoning.
5. Spread the cauliflower in a single layer on the prepared baking sheet, making sure not to overcrowd to avoid steaming. Use multiple sheets if needed.
6. Roast in the oven for 15 to 20 minutes for smaller florets or 20 to 25 minutes for larger pieces or steaks, flipping or tossing halfway through. Roast until the cauliflower is tender, deeply golden, and caramelized on the edges.
7. If adding Parmesan cheese, sprinkle it over the cauliflower during the last 5 minutes of roasting, then return to oven to melt and brown slightly.
8. Optional: Toss with fresh lemon zest, chopped parsley, or red pepper flakes before serving for added brightness and flavor.

Air Fryer Method:
– Use 2 to 3 tablespoons olive oil (omit butter).
– Air fry at 375°F (190°C) for 10 to 15 minutes, shaking or flipping every 5 minutes until golden and tender.