Boil the pasta: Bring a large pot of salted water to a boil. Cook pasta until just al dente. Reserve about 1 cup of pasta water, then drain.
Season the shrimp: Pat shrimp dry.
Season with 1/2 tsp salt and a few grinds of pepper.
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 just opaque. Transfer to a plate.
Build the garlic base: Lower heat to medium.
Add butter to the same skillet. Once melted, add garlic and red pepper flakes. Cook 30–60 seconds until fragrant, not browned.
Deglaze: Pour in white wine (or broth).
Scrape up any browned bits. Simmer 1–2 minutes to reduce slightly.
Creamy sauce time: Stir in heavy cream. Simmer gently 2–3 minutes, stirring, until slightly thickened.
Season with a pinch of salt and pepper.
Add cheese: Reduce heat to low. Sprinkle in Parmesan gradually, stirring until smooth. If too thick, add a splash of pasta water.
Bring it together: Add cooked pasta and shrimp to the skillet.
Toss to coat, loosening with more pasta water until the sauce clings silkily to the noodles.
Brighten: Stir in lemon juice and zest. Taste and adjust salt, pepper, and heat from chili flakes.
Finish and serve: Sprinkle with parsley and extra Parmesan. Serve hot.