Cut cauliflower into uniform 1–1.5 inch florets for even cooking. Mince 2–3 garlic cloves. Pat florets dry with paper towels — dry florets brown better. Move oven rack to center and preheat to 218°C.

Toss florets in a large bowl with 2–3 tbsp olive oil, minced garlic, kosher salt, and black pepper until evenly coated. Spread in a single layer on a large sheet pan — don't crowd them. Roast at 218°C for 22–30 minutes, tossing halfway through. Done when golden brown and tender; smaller florets finish faster, so watch for color rather than the clock.

Cauliflower is done when florets are tender-crisp with golden-brown, caramelized edges — not burnt. Remove from oven and taste a floret to confirm tenderness. Finish with Parmesan, lemon juice, and lemon zest if desired. Serve immediately. Note: crowding the pan prevents browning — use a large pan with florets in a single layer.