Heat the oven: Set to 425°F (220°C). Place the rack in the upper third for better browning.
Cut florets: Break broccoli into medium florets with flat sides so they make good contact with the pan. Slice thick stems into 1/4-inch pieces.
Dry thoroughly: Rinse if needed, then spin or pat very dry with towels. The drier, the crispier.
Toss with oil and seasonings: In a large bowl, combine broccoli, olive oil, salt, pepper, garlic powder, and red pepper flakes if using. Mix until every piece looks lightly glossy.
Spread on a sheet pan: Use a large rimmed baking sheet. Do not crowd. Arrange florets cut-side down for maximum caramelization.
Roast 15 minutes: Let the bottoms brown without stirring.
Toss and finish: Flip or toss, then roast 5–10 minutes more until edges turn deeply golden and crisp, with tender stems.
Brighten and serve: Squeeze fresh lemon over the hot broccoli. Shower with Parmesan if you like. Taste and adjust salt.
Small florets: 15–18 minutes total
Medium florets: 20–25 minutes total
Large florets: 25–28 minutes total
