Cook the Pasta: Boil pasta according to package instructions. Reserve ½ cup of pasta water before draining.
Sauté the Shrimp: In a large pan, melt 2 tablespoons of butter over medium heat. Add shrimp, season with salt and pepper, and cook for 2–3 minutes per side until pink. Remove and set aside.
Garlic Butter Sauce: In the same pan, add 1 tablespoon of butter and garlic. Sauté until fragrant. Add chili flakes (optional), then stir in cream and Parmesan. Let it simmer for 2–3 minutes.
Combine: Return shrimp to the pan, then toss in the drained pasta. Add a splash of pasta water to loosen the sauce if needed.
Finish & Serve: Squeeze lemon juice on top, sprinkle with parsley, and serve hot!