Bring A Large Pot Of Lightly Salted Water To A Boil. Cook Pasta For 8 To 10 Minutes, Or Until Al Dente; Drain. Melt Butter With Olive Oil In A Large Skillet Over Medium Heat. Saute Garlic And Mushrooms Until Tender. Stir In Crawfish And Green Onions; Reduce Heat To Low, And Cook 5 Minutes. Stir In Half And Half, Parmesan Cheese, And Parsley. Simmer For 5 Minutes. Season With Salt And Pepper, And Serve Over Hot Linguine.