Bring a pot of water to boil, then add the pasta. Boil until the pasta is slightly undercooked (7-10 minutes). Add the frozen broccoli florets to the boiling pasta water, turn off the heat and let sit for 1-2 minutes or until the broccoli is tender-crisp. Drain the pasta and broccoli in a colander.

Transfer the pasta and broccoli back to the pot (with the heat off) or to a bowl and add the butter. Toss until the butter has melted and coated everything. Add the parmesan then toss to coat again. Serve immediately.