How to Make It
Bring 10 cups water to a boil in a Dutch oven over high. Add fettuccine, and cook 6 minutes. Add broccoli florets to pasta; cook until pasta is al dente and broccoli is bright green and crisp-tender, about 3 minutes. Reserve 1/2 cup cooking liquid, and set aside. Drain pasta mixture.
Return pasta and broccoli to Dutch oven; reduce heat to low. Stir in pesto, mustard, lemon zest and juice, and salt. Add shrimp, and cook, stirring constantly, just until heated through, about 2 minutes, adding cooking liquid, 1 tablespoon at a time, if needed for creaminess. Top with Parmesan; serve immediately.