Roasted cauliflower can be served as an easy side or as a room temperature make ahead appetizer
Preheat oven to 400 degrees.
Cut cauliflower head into florets. Cut onion in half crosswise, peel, then slice into half moons, about ¼” thick.
Place on baking tray. Toss with olive oil and sprinkle with kosher salt and pepper. Flip cauliflower after 20 minutes.
When cauliflower is ready, remove from oven. Now add the Parmesan cheese and put back in the oven for 5 minutes or just add the Parmesan and cover loosely with foil.
You can sprinkle with some paprika for subtle taste and color. Smoked paprika is preferred over sweet, but either will work.
Serve as a side dish for dinner. Or serve at room temperature as an appetizer or snack.