Sautee in melted butter: Onions, Garlic, Mushrooms, Green Onions, Crawfish Tails, Cajun Seasoning (We use a blend of special Bistreaux spices, but in general one can use Tony Chachere's). Add Heavy Cream. Cook until it comes to a boil and reduces. Add cooked pasta. Sprinkle some Parmesan cheese on top.