Bring a large pot of water to a boil, add a generous pinch of salt, and cook pasta just to al dente, according to package directions.
While the pasta cooks, roughly chop the broccoli florets into small pieces, discarding any thick stems. Add broccoli to the boiling water 2-3 minutes before the pasta’s cooking time is up.
When both the pasta and broccoli are finished, use a liquid measuring cup to scoop out 3/4 cup of the cooking water, then drain pasta and broccoli together. Set aside.
Return the empty pot to medium heat. Add olive oil and garlic. Cook for 30-60 seconds, just until fragrant, then stir in the lemon juice, lemon zest, oregano, red pepper flakes, 1/2 teaspoon salt, and 10-12 cranks of fresh-ground black pepper. Whisk in about 1/2 cup of the reserved pasta water.
Return the pasta and broccoli to the pot. Add the Parmesan cheese. Stir well, then taste. Add a bit more pasta water to further thin out the sauce, if desired, or more lemon, salt, or pepper to taste.
Serve right away with a few sprigs of fresh parsley, lemon wedges, and extra pepper and Parmesan.