1. Heat butter just until melted; remove from heat. Add flour, salt, pepper and mustard; with wooden spoon, stir until smooth. Add milk slowly, stirring constantly. Return to heat.

  2. Over medium heat, bring to boil; stir constantly. Add cheese; stir over low heat just until melted. Remove from heat. Makes 3 cups.

  3. Drain spinach well. In the butter in a 10-inch skillet, saute spinach and mushrooms; stir 2 minutes. Remove from heat. Reserve 1/2 cup cheese sauce. Combine rest of sauce with spinach-mushroom mixture; mix well.

  4. Preheat oven to 350°F. Assemble crepes on buttered, heat proof serving dish or cookie sheet. Place one crepe on dish. Spread with 1/2 cup filling. Top with another crepe.

  5. Continue stacking crepes and filling. End with plain crepe on top. Cover completely with foil; heat in oven 20 minutes. Remove foil. Spoon reserved cheese sauce over top. Garnish with sliced mushroom and parsley. Cut into wedges.