Preheat oven to 450° F. Trim the Brussels sprouts and cut them in half. Place them in a bowl and toss with olive oil and a pinch of salt.
Arrange the Brussels sprouts cut side down on a baking sheet. Roast for 20–22 minutes, turning halfway through, until browned and charred to your liking. Set aside to cool slightly.
While the Brussels sprouts roast, chop the romaine lettuce and slice the red onion.
In a large bowl, combine the romaine, roasted Brussels sprouts, red onion, Parmesan, and croutons.
Add Caesar dressing to taste and toss until everything is evenly coated. Serve immediately.
