1. Preheat oven to 450.
2. Toss cauliflower, oil, marjoram, salt and pepper in a large bowl. Spread on a large rimmed baking sheet and roast until starting to soften and brown on the bottom, 15 to 20 minutes. Toss the cauliflower with the vinegar and sprinkle with the cheese. Return to the oven and roast until the cheese is melted and any moisture has evaporated, 5 to 10 minutes more.
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