In a large pot, bring salted water to a boil. Add the fettuccine and cook according to package instructions until al dente. Drain and set aside.
In a mixing bowl, toss the cleaned shrimp with Cajun seasoning until well coated.
In a large skillet, heat the olive oil over medium-high heat. Add the seasoned shrimp and cook for about 2-3 minutes per side, or until they turn pink and are cooked through. Remove the shrimp from the skillet and set aside.
In the same skillet, reduce heat to medium and add the butter. Once melted, sauté the minced garlic for about 30 seconds until fragrant.
Slowly pour in the heavy cream, stirring constantly. Bring to a gentle simmer, then add the grated Parmesan cheese, stirring until the cheese is melted and the sauce is smooth. Season with salt and pepper to taste.
Add the cooked fettuccine and sautéed shrimp to the sauce, tossing to coat everything evenly. Heat through for another 2 minutes.
Plate the dish and garnish with chopped parsley for a pop of color.