Steam the broccoli florets until fork-tender, about 7–9 minutes.

In a blender, combine broccoli, garlic, lemon juice, olive oil, Parmesan, salt, and pepper. Blend until creamy.

Cook pasta shells in salted boiling water until al dente. Reserve 1/2 cup pasta water and drain.

Return pasta to the pot and toss with the broccoli sauce. Add pasta water as needed for creaminess.

Serve with extra Parmesan and a few whole broccoli florets for garnish.