Boil the pasta: Bring a large pot of salted water to a boil.
Cook pasta until just shy of al dente. Reserve 1 cup of pasta water, then drain.
Season the shrimp: Pat shrimp dry and season with a pinch of salt and pepper. Dry shrimp sear better and stay juicy.
Sear the shrimp: Heat olive oil in a large skillet over medium-high.
Add shrimp in a single layer and cook 1–2 minutes per side until pink and opaque. Transfer to a plate.
Build the flavor base: Reduce heat to medium. Add butter to the same skillet.
Stir in garlic and red pepper flakes and cook 30–45 seconds until fragrant. Do not brown the garlic.
Deglaze: Pour in white wine (or broth). Scrape up browned bits and simmer 1–2 minutes to reduce slightly.
Make it creamy: Stir in heavy cream.
Simmer gently 2–3 minutes until the sauce thickens slightly. Keep it to a gentle bubble—boiling can cause separation.
Add cheese and lemon: Lower the heat and whisk in Parmesan until melted and smooth. Add lemon zest and juice.
Taste and season with salt and pepper.
Bring it together: Add the cooked pasta and half the shrimp to the skillet. Toss, adding splashes of pasta water as needed to loosen and emulsify the sauce. You want it glossy and clinging to the noodles.
Finish and serve: Fold in remaining shrimp and parsley.
Adjust seasoning and lemon to taste. Serve hot with extra Parmesan and a pinch of red pepper flakes if you like heat.