Cook fettuccine in boiling salted water according to package instructions until al dente. Drain and set aside.
In a skillet over medium-high heat, melt 1 tbsp of butter. Add minced garlic and sauté until fragrant. Add shrimp with half of the Cajun seasoning; cook until pink (about 3 minutes). Remove shrimp from skillet.
In the same skillet, add another tbsp of butter. Season steak with salt, pepper, and remaining Cajun seasoning; cook to desired doneness (about 4 minutes per side for medium-rare). Let it rest before slicing.
Lower heat and pour heavy cream into the skillet, stirring continuously. Gradually add Parmesan cheese until melted into a creamy sauce.
Combine the cooked pasta and sautéed shrimp in the sauce; toss until well-coated.
Serve immediately garnished with extra Parmesan if desired.
