Thaw crab meat, retain liquid and seperate into chunks. In saucepan, saute' onions, celery and mushrooms in butter or margarine for 2 to 3 minutes. Remove with a slotted spoon and set aside.
Stir flour into remaining butter drippings until smooth. Add milk and crab liquid. Cook until thickened.
Stir in cheese, salt, pepper, and nutmeg in small bowl. Toss together crab, onions, celery, mushrooms and 1/2 cup of cauce. Season to taste.
Spread equal amount of filling accross center of each crepe and roll up or fold over.
Place in a shallow baking pan and pour remaining sauce over top. Sprinkle with Parmesean cheese if desired,
Heat in 350 oven for 10 to 15 minutes.
Makes 8 crepes.