Prep the broccoli: Rinse and pat dry. Cut into large florets, leaving a bit of stem on each piece. Aim for golf ball to small lime size—big enough to smash without falling apart.

Steam until just tender: Bring an inch of water to a boil in a pot fitted with a steamer basket. Add broccoli, cover, and steam 4–6 minutes until a fork slides in with slight resistance. You want it tender but not soft.

Dry it well: Transfer broccoli to a clean kitchen towel or paper towels and blot dry. Moisture is the enemy of crispiness, so take a minute here.

Make the seasoning oil: In a bowl, mix olive oil, garlic, salt, pepper, red pepper flakes (if using), and lemon zest. This coats the florets and boosts browning.

Toss and coat: Gently toss the broccoli in the bowl until evenly coated. If it looks dry, add another teaspoon of oil.

Preheat the air fryer: Set it to 400°F (200°C) for 3 minutes. Lightly oil or spray the basket to prevent sticking.

Smash the florets: Place the broccoli on a cutting board. Use the bottom of a glass, a measuring cup, or a small plate to gently press each floret until flattened to about 1/2 inch. Keep them intact, but create lots of craggy edges.

Arrange in the basket: Lay smashed florets in a single layer with a little space between each piece. Work in batches if needed. Crowding will steam them instead of crisping.

Air fry, flip, and finish: Cook at 400°F for 8–10 minutes total, flipping halfway. In the last 2 minutes, sprinkle Parmesan over the tops so it melts and crisps.

Finish with lemon: Transfer to a plate, squeeze on lemon juice, and adjust salt and pepper. Serve hot while the edges are ultra-crispy.