Preheat the oven to 425°F. Spray a rimmed baking sheet with nonstick spray, or line with parchment paper or aluminum foil.
Cut the broccoli into small or bite-sized pieces (see recipe intro) and place them on the baking sheet. Drizzle over 2 tablespoons of the olive oil and sprinkle over the sliced garlic. Use you hands to toss the broccoli, and then spread it out in an even single layer on the baking sheet. Sprinkle with salt and pepper and roast for 25 minutes, until the broccoli is crisp-tender, and the edges of the broccoli are browned in places.
Toss the hot broccoli with the lemon juice, zest and Parmesan. Taste and add additional salt and pepper as needed.