Fill a large pot with lightly salted water and bring to a rolling boil. Cook fettuccine at a boil until tender yet firm to the bite, about 8 minutes. Drain.

Heat butter in a large skillet over medium heat. Cook and stir shrimp and garlic in butter for 1 minute. Pour in half-and-half; stir. Add Parmesan cheese, 1 tablespoon at a time, stirring constantly. Mix in parsley; season with salt. Simmer, stirring frequently, until sauce is thickened.