Make crepe batter by placing flour into a bowl. Make a well in the center and add egg, yolk and salt. Combine slowly with milk to form a smooth batter. Allow to stand 4 hours. Melt 1 tablespoon of butter in a crepe pan. Place a small ladleful of batter into the pan and roll it around until it covers the pan base. Cook until waxy bubbles appear on the surface then turn the crepe over with a palette knife. Finish cooking and remove to a plate. Continue until 8 crepes are made.
Poach celery for 5 minutes in boiling salted water. Place clarified butter into a casserole dish on top of the stove. Add the carrot and onion and fry until golden. Add the chicken, cover and allow to steam 10 minutes. Add cold water to cover, bring to a boil, and simmer for 1 1/4 hours. Remove chicken and cut into small pieces and reduce chicken stock to 2 1/2 cups. Strain.
To make the sauce, melt the butter in a pan and add the flour. Stir to form a roux and whisk in the milk to form a thick sauce. Season with salt, pepper and nutmeg. Add the wine and simmer 10 minutes. Add the chicken stock and simmer 5 minutes longer. Add poached celery to the chicken flesh and then combine with 2 cups of the sauce. Add 3 tablespoons of cheese to remaining sauce. Lay crepes onto an ovenproof dish. Place a heaping tablespoon of the celery and chicken mixture in the center of each crepe. Fold and turn over. Coat with cheese sauce. Sprinkle with the remaining cheese and place under the broiler to brown (about 5 minutes). Serve sprinkled with cayenne pepper and garnished with finely chopped parsley.