Pat the shrimp dry: Use paper towels to remove excess moisture. Season lightly with salt and pepper.
Dry shrimp sear better and stay juicy.
Sear the shrimp: Heat the olive oil and 1 tablespoon butter in a large skillet over medium-high heat. Add shrimp in a single layer and cook 1–2 minutes per side, just until pink and opaque. Transfer to a plate.
Do not overcook.
Sauté the garlic: Reduce heat to medium. Add remaining 1 tablespoon butter and the minced garlic. Cook 30–45 seconds until fragrant, stirring so it doesn’t brown.
Deglaze the pan: Pour in the broth (or wine).
Scrape up browned bits with a wooden spoon. Simmer for 1–2 minutes to reduce slightly.
Add cream and Parmesan: Stir in the heavy cream and Parmesan. Simmer on medium-low for 2–3 minutes, stirring until the cheese melts and the sauce thickens enough to coat a spoon.
Brighten the flavor: Add lemon zest, lemon juice, and red pepper flakes if using.
Taste and season with salt and pepper.
Return shrimp to the pan: Add the shrimp and any juices on the plate. Toss to coat and warm through for 30–60 seconds. Do not boil.
Finish and serve: Sprinkle with parsley.
Serve immediately over pasta or rice, or with bread for dipping. The sauce will thicken slightly as it rests.