Prep: Preheat your oven to 220°C/200°C fan/425°F/Gas 7.
Trim the sprouts: Trim the ends of the Brussels sprouts and remove any damaged or loose outer leaves. Cut the larger sprouts in half or quarters, depending on their size, so they cook evenly.
Season the sprouts: Put the sprouts onto a large baking tray with the olive oil, chopped garlic, salt and pepper. Toss everything together until evenly coated.
Arrange and roast: Spread the sprouts into a single layer, cut-side down where possible. Roast for 25 minutes, until they are starting to turn golden brown.
Smaller sprouts may be ready for the next step slightly sooner.
Add the Parmesan: Sprinkle over the grated Parmesan and return to the oven for another 10 minutes, until the sprouts are golden, crispy and tender.
Notes
Dry the sprouts well and avoid overcrowding the tray for the best crispy edges.
Keep the garlic in chunks so it is less likely to burn.
Cut larger sprouts into similar-sized pieces for even cooking.
Add fresh thyme or rosemary for extra flavour, or swap the Parmesan for paprika and chilli.
You can add diced bacon before roasting for a more indulgent variation.
Preparation and roasting times can vary depending on the size of your sprouts and your oven.