Boil the pasta: Bring a large pot of salted water to a boil. Cook the protein penne until just al dente per package directions.
Reserve 1/2 cup pasta water, then drain.
Season the shrimp: Pat the shrimp dry. Season lightly with salt and black pepper. This helps them sear and stay juicy.
Sear the shrimp: Heat the olive oil and 1 tablespoon butter 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.
Sauté the aromatics: Reduce heat to medium. Add remaining 1 tablespoon butter.
Stir in minced garlic and red pepper flakes. Cook 30–60 seconds until fragrant, not browned.
Deglaze: Pour in the wine (or broth), scraping up any browned bits. Let it simmer 1–2 minutes to reduce slightly.
Create the sauce: Stir in the heavy cream and 1/2 cup broth.
Simmer gently 2–3 minutes until it starts to thicken. Avoid a hard boil to prevent splitting.
Add cheese and lemon: Lower the heat. Stir in Parmesan until melted and smooth.
Add lemon zest and 1 tablespoon lemon juice. Taste and adjust with more lemon if you like it brighter.
Combine everything: Return shrimp and any juices to the pan. Add the drained penne.
Toss to coat, adding splashes of reserved pasta water as needed to loosen and silk up the sauce.
Finish and serve: Sprinkle with parsley, season with salt and pepper, and top with extra Parmesan. Serve hot with a wedge of lemon on the side.