Preheat oven to 400 degrees F.
Cut the cauliflower into 1" steaks. Place them on parchment paper on a baking sheet. Brush both sides with olive oil. Sprinkle with salt.
Transfer the cauliflower to a baking sheet and spread in an even layer.
Bake the cauliflower for 10 minutes. Remove from the oven and turn the steaks over, being careful not to break them apart. Sprinkle on the rosemary and parmesan cheese and return to the oven.
Bake for an additional 10 minutes, or until the tops are golden brown and the cheese is melted and browning.
