Wash spinach thoroughly and steam until tender (about 10 minutes).
Press excess liquid out and place spinach in a grinder fitted with a fine blade.
Meanwhile, saute" onion in margarine until tender.
Stir in cooked and minced spinach until well blended.
Add flour and cook again.
Stir in milk and cook until sauce is thickened.
Finally add cheese and season to taste.
Divide spinach among crepes; roll up and place in a well-greased baking dish.
Cover with foil.
Bake immediately at 350° for 30 minutes or refrigerate and bake as needed for 40 minutes.