Preheat your oven to 425°F (220°C). Line a large sheet pan with parchment paper or a silicone baking mat to prevent sticking and make cleanup easier.

Trim the tough ends from the broccoli stems and cut into large florets, about 1½–2 inches each. Rinse well and dry thoroughly by shaking off excess water or patting dry with a clean kitchen towel so the broccoli can crisp in the oven.

Bring a large pot of salted water to a boil. Add the broccoli florets and cook for 3–4 minutes, until bright green and just starting to turn tender when pierced with a fork. They should not be fully cooked.

Using a slotted spoon, transfer the broccoli to a colander. Rinse quickly under cold water or plunge into an ice bath to stop the cooking. Drain very well, shaking the colander to remove as much moisture as possible.

In a large bowl, combine the par-boiled broccoli with 2 tablespoons of olive oil, 1 teaspoon of kosher salt, and the black pepper. Toss gently to coat, trying not to break the florets apart too much.

Spread the broccoli out in a single layer on the prepared sheet pan, leaving space between each floret so they roast and crisp instead of steam.

Use the bottom of a sturdy drinking glass, measuring cup, or small plate to gently press each floret down until it is about ½ inch thick. Flatten enough to increase the surface area but not so much that the florets fall apart completely.

In a small bowl, stir together the remaining 1 tablespoon olive oil, minced garlic, remaining ½ teaspoon kosher salt, red pepper flakes (if using), and smoked or sweet paprika. Brush or spoon this mixture evenly over the smashed broccoli, distributing the garlic bits on top.

Roast the smashed broccoli for 18–22 minutes, until the edges are deeply browned and crisp and the stems are tender. Start checking around 16–17 minutes; you’re aiming for dark golden-brown edges.

Remove the pan from the oven and sprinkle the grated Parmesan evenly over the broccoli. Return to the oven for 3–5 minutes, just until the cheese melts and begins to brown in spots.

Take the pan out of the oven. Drizzle the melted butter over the hot broccoli, if using. Sprinkle the lemon zest on top and add 1–2 teaspoons of fresh lemon juice, to taste. Scatter the chopped parsley (or other herbs) over everything. Taste and adjust with a bit more salt or lemon juice if needed.

Serve the smashed broccoli immediately while hot, crispy, and cheesy. It pairs well with roasted chicken, steak, fish, tofu, beans, or grains like quinoa and farro.