Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
Remove the leaves from the cauliflower and trim the stem so it sits flat.
Cut the cauliflower into thick 1-inch slices (you’ll get about 3 to 4 steaks).
Brush both sides with olive oil and season with garlic powder, paprika, salt, and pepper.
Place the cauliflower steaks on the baking sheet and roast for 20 minutes, flipping halfway through.
Sprinkle the cheddar and Parmesan over the steaks and bake for another 10 minutes until golden and bubbly.
Garnish with fresh parsley before serving warm.