Cook the fettuccine in salted boiling water according to package instructions; drain and set aside.

In a large skillet, melt the butter over medium heat. Add the garlic and sauté for about 1 minute until fragrant.

Add the shrimp to the skillet and sprinkle with Cajun seasoning. Cook until the shrimp are pink and opaque, about 3-4 minutes.

Stir in the heavy cream and bring to a simmer. Cook for 2-3 minutes until slightly thickened.

Mix in the cooked fettuccine and Parmesan cheese, tossing to combine. Cook for an additional minute.

Garnish with green onions and parsley before serving.