1 head cauliflower
1 onion, sliced
4 thyme sprigs, or ½ teaspoon dried thyme
4 garlic cloves, sliced thin
3 tablespoons olive oil
Kosher salt and pepper to taste
½ cup grated Parmesan cheese
Preheat oven to 425°. Cut cauliflower into florets and toss with onions and place them on a large rimmed baking sheet. Sprinkle with thyme, garlic and olive oil. Season with salt and pepper.
Roast, tossing occasionally, until almost tender, 35-40 minutes. Sprinkle with grated Parmesan, toss to combine, and roast until cauliflower is tender, 10-12 minutes longer.