Preheat oven to 450°F. Line a large rimmed baking sheet with parchment paper.
Toss 16 ounces broccoli florets, 2 tablespoons olive oil, ¼ teaspoon salt and ¼ teaspoon pepper in a large bowl until well coated. Arrange the florets in an even layer on the prepared baking sheet. Roast until tender, about 15 minutes.
Meanwhile, toss 1 cup Parmesan and 1 teaspoon garlic powder together in a small bowl.
Remove the broccoli from the oven; top each floret with 1 to 2 teaspoons cheese mixture. Bake until the cheese is lightly golden, about 3 minutes. Remove from oven and allow cheese to set for 1 minute before serving. Serve the broccoli with the crispy cheese bits from the baking sheet.
