Preheat oven to 400 degrees f.

Trim and halve the Brussels sprouts, and place in a large glass bowl.

Add the oil and grated Parmesan, and sea salt.

Toss well to coat well, then place everything on a large, rimmed baking tray.

Distribute sprouts evenly in a single layer on the tray.

Roast in your preheated oven for 15-20 minutes, turning once in the middle of roasting time, until golden brown with crunchy outer shells, and the center of the sprouts are tender-crisp.