Bring a large pot of salted water to a boil. Add pasta and cook until al dente, according to package directions. Reserve 1 cup of pasta water before draining.

During the last 3–4 minutes of cooking, add the broccoli florets to the boiling pasta water. Drain together and set aside.

In a large skillet, heat olive oil over medium heat. Add garlic and sauté until fragrant and just golden, about 1–2 minutes.

Add pasta and broccoli to the skillet, tossing to coat in the garlic oil. Pour in a splash of reserved pasta water to create a light sauce.

Stir in lemon juice, zest, salt, and black pepper. Add Parmesan and red pepper flakes if using. Toss again until glossy and well combined.

Serve warm with extra Parmesan and a drizzle of olive oil on top.