In a large pot, bring salted water to a boil. Add the fettuccine and cook according to package instructions until al dente. Reserve ½ cup of pasta water, then drain the rest.
In a large skillet over medium heat, melt 2 tablespoons of butter. Add the shrimp and season with salt and pepper. Cook until the shrimp turn pink and opaque, about 2-3 minutes per side. Remove the shrimp from the skillet and set aside.
In the same skillet, add the remaining 2 tablespoons of butter and the minced garlic. Sauté for about 1 minute until fragrant, being careful not to burn the garlic.
Pour in the heavy cream and bring to a gentle simmer, stirring occasionally. Sprinkle in the Italian seasoning and season with a pinch of salt and black pepper.
Gradually stir in the grated Parmesan cheese, allowing it to melt and thicken the sauce. If the sauce becomes too thick, add reserved pasta water a little at a time until desired consistency is reached.
Add the drained fettuccine and cooked shrimp back into the skillet. Toss everything together to coat the pasta and shrimp in the creamy garlic sauce.
Remove from heat and garnish with freshly chopped parsley. Serve immediately.
Notes
For a spicier version, add red pepper flakes to the sauce.