1. Preheat oven to 450 degrees F.
2. Toss cauliflower, oil, marjoram, salt, and pepper in a large bowl. Spread on a large baking sheet and roast until soft and brown on the bottom (15-20 minutes).
3. Toss the cauliflower with vinegar and sprinkle with cheese. Return to the oven and roast until the cheese is melted and any moisture has evaporated (5 minutes).