Preheat oven to 400 degrees F, adjust oven rack to low.
In a saucepan, simmer chicken with broth till just done, about 8 to 10 minutes. If time allows, cool the chicken in the broth and then shred, reserving both chicken and broth.
Heat oil to medium-high in a one and a half to two-quart saucepan and saute onions, carrots, and celery till just tender, about five minutes. They will cook more in the oven. Season with salt and pepper and add to chicken.
In the same pan that you used for the vegetables, melt butter and add flour, cooking one minute. Whisk in chicken broth, milk, marjoram, and any accumulated chicken juices. Bring to a simmer and reduce to low, simmering about one minute till sauce fully thickens, stirring constantly. Add sherry, taste, and adjust any seasonings.
Add chicken and vegetables to the saucepan, add peas and gently stir. May be refrigerated for a day or two. Gently reheat to warm the filling before proceeding.
If using puff pastry or pie crust, add 1/4 cup of extra broth; those topping options take longer to cook; the filling will be drier if the longer time is not compeensated for wth a bit mroe liquid. Place in a casserole or a 13 x 9 inch pan, cover with topping of choice and bake until topping is golden brown and filling bubbly, about 30 minutes for biscuit options or mashed potatoes, 40 to 50 minutes for puff pastry. You may also bake in individual ramekins for 20 to 25 minutes for biscuit or mashed potato topping, 35 to 40 for puff pastry or pie crust.
See the post for information on toppings.
Nutrition: (Without topping, which can vary) Per Serving: 261 Calories; 11g Fat (38.3% calories from fat); 24g Protein; 15g Carbohydrate; 2g Dietary Fiber; 68mg Cholesterol; 362mg Sodium. Exchanges: 1/2 Grain(Starch); 3 Lean Meat; 1 Vegetable; 0 Non-Fat Milk; 2 Fat.
Keywords: Bargain Meal of the Week, Carrots, Casserole, Chicken, chicken pot pie, Heritage Recipe, leftover Chicken, leftover vegetables, Leftovers, Pam Anderson, Peas, Turkey Leftovers, White sauce