Cook spaghetti according to package instructions.

In a skillet, cook beef until browned; set aside. Sauté shrimp with Cajun seasoning until pink; set aside.

In the same skillet, melt butter, add garlic, then stir in cream and Parmesan. Simmer until thickened.

Return beef and shrimp to the sauce, add cooked spaghetti, and toss to combine.

Serve hot, garnished with extra Parmesan or parsley if desired.