Cook linguine according to package directions; drain. Keep warm.
Melt butter in a Dutch oven over medium heat. Add flour, and cook, stirring constantly, 2 minutes or until blended. Add green onions and next 4 ingredients; sauté 5 minutes or until tender. Add bouillon cube and next 7 ingredients; cook 10 minutes or until thickened. Stir in hot sauce, if desired. Serve over linguine noodles; sprinkle with shredded Parmesan cheese. Garnish, if desired.
*2 pounds peeled, medium-size fresh or frozen shrimp can be substituted for crawfish tails.