• Remove meat from the chicken carcass, cut into 1/2-inch dice, discard the skin and bones and set aside the diced chicken.
• Melt 2 Tablespoons butter and 1 Tablespoon olive oil in a large frying pan, add onions, carrots, celery, and potatoes. Sauté the vegetables, stirring occasionally for about 20 minutes until softened and slightly caramelized.

Make the Gravy

• While vegetables are cooking make the gravy: Finely chop the mushrooms.
• Melt 5 Tablespoons butter in a medium saucepan over medium heat.
• Add chopped mushrooms to the butter and cook for 5 minutes, until the mushrooms have released their liquid.
• Add the flour and stir constantly, the mixture will become pasty, the flour may stick to the bottom of the pan, this is okay. Cook for about a minute.
• Add the broth 1/4 cup at a time, stirring to release the bits from the bottom of the pan. Continue adding the broth while stirring constantly until all the broth is added. Bring the mixture to a boil then turn down to a low boil. Stir and boil for 5 minutes, until slightly thickened.
• Once the vegetables are cooked add the thyme, salt and pepper and stir to combine.
• Combine the cooked vegetables, cut up chicken, and gravy in one pan. Stir well and taste. Add more salt and pepper to your taste. Set aside to cool slightly.
• Heat oven to 400°F.

For Individual Pot Pies:

• Divide the slightly cooled mixture among eight 10 to 12 ounce oven-proof bowls or ramekins. 
• Roll the pastry out to 1/8″ thickness.
• Cut 5 rounds that measure about 1″ larger than the top of the individual bowls of chicken and vegetable mixture. Re-roll scraps and cut the remaining 3 rounds.
• Make an egg wash by beating the egg with 1 Tablespoon water. Brush the egg wash onto the rims of the oven proof dishes, this will act as the “glue" so the pastry adheres.
• Lay the pastry rounds on top of the bowls and pinch the edges to seal the dish.
• Brush pastry with egg wash.
• With a small, sharp knife make slits in the top of the pastry to act as air vents.
• Put the ramekins onto a baking sheet and bake at 400º F for 25-35 minutes, until filling is bubbly and crust is golden brown.

For One Family Style Pot Pie:

• Pour the mixture into a 2-quart oven-safe casserole dish. 
• Roll the pastry out until it is 1 1/2" larger than that diameter of the dish. 
• Lift the pastry onto the dish and tuck the dough in around the edges of the meat and veggie mixture. 
• Make an egg wash by beating the egg with 1 Tablespoon water. Brush pastry with egg wash.
  
• With a small, sharp knife make slits in the top of the pastry to act as air vents.
  
• Put the casserole onto a baking sheet and bake for 45 to 55 minutes, until the top is golden brown and the meat mixture is bubbling.