Preheat the oven to 400 degrees Fahrenheit (use the convection setting if you have it).
Prepare the Brussels sprouts and garlic as noted above. Place them in a large bowl and mix them with the olive oil, salt, pepper and Parmesan cheese until fully coated.
Line a baking sheet with parchment paper. Place the Brussels sprouts on the sheet in a single layer, cut side up.
Roast for 23 to 27 minutes (with the standard oven setting) or 15 to 20 (with the convection oven setting), until browned and crispy on the outside and tender when pricked with a fork. Enjoy immediately.