Cut 1 carrot and 1 stalk of celery into large dice, and peel and quarter 1 yellow onion. In a large stockpot, place the chicken, diced vegetables, onion, 1 bay leaf and peppercorns, cover with water, and bring to a boil over high heat. Lower heat to a simmer and cook the chicken until tender, 20 to 30 minutes, skimming the foam which may form on the surface. Remove the chicken from the pot and let cool. Strain the stock into a clean stockpot and reduce over high heat to 3 cups, then cool. Skin and bone the chicken, and discard. Cut the meat into 1-inch pieces and set aside.

Make the pie dough by combining the flour and salt in a medium bowl. Add the butter and work with your hands until the mixture resembles coarse crumbs. Using the tines of a fork, stir in the water 1 tablespoon at a time, and work with your hands just until a smooth ball forms, being careful not to overwork the dough. Wrap in plastic and refrigerate for 20 minutes.

Peel and dice the remaining 2 carrots and onion, and dice the remaining 2 stalks of celery.

In a medium pot blanch the carrots and peas in boiling water until just cooked through, about 2 minutes. Drain and reserve.

Preheat the oven to 400 degrees F.

In a large skillet or pot, melt the butter over medium high heat. Saute the onions and celery until soft, about 3 minutes. Add the garlic and mushrooms to the pan and continue cooking until the mushrooms are soft and give off their liquid, about 5 minutes. Add Essence. Sprinkle the flour into the vegetables to make a roux, cooking for 2 to 3 minutes to slightly thicken. Add the wine, cream and cold stock, stirring well. Add the chicken and parsley, and season to taste with salt and pepper.

Transfer the chicken mixture to a large skillet or casserole dish, or divide among 8 (2-cup) baking dishes.

Remove the dough from the refrigerator and place on a floured surface. Roll out the dough to fit the skillet, or cut into 8 shapes to top the 2-cup casserole dishes. Gently transfer to the skillet, turning the edges under to seal. Brush the top of the pastry with the egg wash and cut a pattern of slits over the crust. Bake until the crusts are golden brown and the contents are hot and bubbly, about 10 to 15 minutes.

Combine all ingredients thoroughly and store in an airtight jar or container. Yield: about 2/3 cup