Preheat the oven to 400F / 200c and line a baking sheet with parchment.
Mix together the oil, onion powder, garlic powder, salt, pepper and parmesan in a small ball and set to one side.
Cut the cauliflower in half through the stalk, then cut two steaks, about an inch and a half in thickness.
Brush the cauliflower steaks all over with the oil mix and place in the oven.
Cook for 25 to 30 minutes, flipping halfway so that they get crispy all over.
Once browned, take them out of the oven and turn on the broiler.
Sprinkle a couple of tablespoons of grated cheddar on top of the cauliflower steaks, then place under the broiler for a few minutes til the cheese is melted and bubbly.
Serve with a sprinkle of fresh parsley.