Melt 2 tablespoons of the butter in a large deep skillet over medium heat. Place the shrimp in the skillet and sprinkle with the cajun seasoning and cayenne pepper. Cook until the shrimp turn pink, 4 to 5 minutes. Remove the shrimp from the skillet.
In the same skillet, still over medium heat, melt the remaining 2 tablespoons of butter. Cook the garlic until fragrant, 1 to 2 minutes. Stir in the parmesan and cream and cook, stirring often, until creamy and well combined, about 5 minutes.
Stir the pasta into the sauce and cook for 10 minutes, or until the noodles are softened. Divide the pasta among six plates or shallow serving bowls and top evenly with the cooked shrimp. Garnish green onions, if desired.
Notes
Net carbs 2.2g*Cajun and creole seasonings contain cayenne pepper. This recipe has and extra 1/4 teaspoon of cayenne pepper. You can leave it out if you don't like extra spicy foods!*If you don't want it be be spicy at all you leave out the Cajun seasoning. Instead use 1/2 teaspoon salt, 1/4 teaspoon pepper and 1 teaspoon Italian seasoning.