Fill a large pot with lightly salted water and bring to a rolling boil. Add fettuccine and cook until al dente, about 8 minutes. Drain and set aside.

In a large skillet over medium heat, melt 2 tablespoons of butter. Add shrimp, season with salt and pepper, and cook until pink and opaque, about 2–3 minutes per side. Transfer shrimp to a plate.

Reduce heat to low, add remaining butter to the skillet. Stir in garlic and cook until fragrant, about 1 minute. Pour in heavy cream and simmer, stirring often, until slightly thickened, about 3–4 minutes.

Whisk in Parmesan cheese until the sauce is smooth. Return shrimp to the skillet along with cooked fettuccine. Toss gently to coat in the rich Alfredo sauce.

Sprinkle chopped parsley over the pasta and serve immediately.