Preheat the oven. Set your oven to 425°F (220°C).
A hot oven is key for browning. Place a large baking sheet inside while it heats to help jump-start the roasting.
Prep the cauliflower. Remove the leaves and core. Cut into evenly sized florets, about 1 to 1.5 inches. Even sizing helps everything roast at the same rate.
Dry the florets. Pat the cauliflower dry with a clean towel.
Moisture keeps it from crisping, so this step matters.
Season. In a large bowl, toss the florets with olive oil, garlic, salt, pepper, and paprika. Make sure each piece is lightly coated without pooling oil.
Pre-roast. Carefully remove the hot baking sheet and spread the cauliflower in a single layer, cut sides down when possible. Leave a little space between pieces for air circulation.
Roast. Bake for 15 minutes, then stir or flip the florets.
Roast another 10–12 minutes until the edges are deep golden brown and the centers are tender.
Add Parmesan. Sprinkle the grated Parmesan over the cauliflower and return to the oven for 2–3 minutes. The cheese should melt and cling to the florets without burning.
Finish with lemon. Transfer to a serving bowl. Toss with lemon juice and a little extra Parmesan, if you like.
Garnish with parsley.
Serve. Enjoy hot as a side dish, or pile it over grains, toss with pasta, or use it as a topping for salads.