Preheat oven to 425°F. Bring a large pot of salted water to a boil.
Wash Brussels sprouts and trim ends. Cut in half if they are large. Add to pot and boil for 8-10 minutes until bright green and tender all the way through. Drain well.
In a bowl, toss boiled Brussels sprouts with olive oil, ¼ cup of parmesan cheese and salt and pepper. Spread evenly onto a roasting pan.
Use a glass or ramekin to flatten the Brussels sprouts. Sprinkle with remaining parmesan cheese. Bake for 15-20 minutes until cheese is golden.
Notes
Leftover smashed Brussels sprouts will keep in an airtight container in the refrigerator for up to 4 days.
Recrisp them under the broiler or in an air fryer.
Freeze in a freezer bag for up to 4 weeks and thaw in the refrigerator before reheating.