Place chicken in large kettle with 5 cups water, celery, onion, bay leaf, salt & pepper. Brint to boil; reduce heat, cover & simmer 45 to 60 minutes until chicken is tender. Remove chicken and set aside.

Using a sieve lined with several layers of cheescloth, strain broth into a large broth. Discard vegetables & skim fat from broth. Measure 1-1/2 cups of broth, reserving remainder for another use.

When chicken is cool, pull meat from bones and cut meat into 1/2" cubes. Discard skin and bones.

Preheat oven to 400 degrees. In a large saucepan, melt butter over medium heat, add mushrooms, leeks, celery & red pepper. Cook about 3 minutes, until tender. Stir in flour, poultry seasoning, salt & pepper. Add the broth & cream all at once; cook & stir until thickened & bubbly. Stir in chicken & peas.

Pour into a round 1.5 qt. Casserole. Unfold piecrust & cut into a circle 2" larger in diameter than top of casserole. Brush edge of casserole with egg. Place crust atop casserole; turn edge under & flute to edge. Cut a 1" hole in center of crust to vent. Cut pastry scraps into decorative shapes; brush top of crust with egg & lay on the scraps, brush again with egg.

Bake in a 400 degree oven for 30 to 40 minutes, until the crust is golden brown. Serve immediately.