In a large pot, bring salted water to a boil. Add the fettuccine pasta and cook according to package instructions until al dente. Reserve 1 cup of pasta water, then drain the pasta and set aside.
In a medium skillet over medium heat, melt 2 tablespoons of butter. Add the minced garlic and sauté for about 1 minute until fragrant.
Add the shrimp to the skillet and season with salt, pepper, and Italian seasoning. Cook for about 2-3 minutes on each side until the shrimp is pink and opaque. Remove the shrimp from the skillet and set aside.
In the same skillet, lower the heat and add the remaining 2 tablespoons of butter. Once melted, pour in the heavy cream and whisk to combine. Let it simmer gently for about 2 minutes.
Gradually add the grated Parmesan cheese to the sauce, whisking continuously until the cheese is melted and the sauce is creamy. If the sauce is too thick, add some reserved pasta water to reach desired consistency.
Combine the cooked fettuccine pasta and shrimp with the Alfredo sauce, tossing to coat everything evenly. Adjust seasoning with salt and pepper as needed.
Serve hot, garnished with chopped parsley if desired.