Preheat the oven to 400 degrees F. Lightly grease 6 (10-ounce) ramekins.
In a medium saucepan, melt the butter over medium heat. Add the onions and celery and saute for 3 to 4 minutes. Add the mushrooms, garlic, and a pinch of salt and cook for 4 to 5 minutes. Stir in the flour and cook, stirring constantly, for about 3 to 4 minutes to make a blond roux. Stir in the chicken stock and bring the liquid up to a boil. Reduce to a simmer and continue to cook for 4 to 6 minutes, or until the sauce starts to thicken. Stir in the half-and-half, bring to a simmer, and continue to cook for 4 minutes. Stir in the remaining salt and pepper, potatoes, carrots, peas, chicken, poultry rub, poultry seasoning, cayenne, and parsley. Mix the filling thoroughly and adjust seasonings with salt and pepper, if needed. Divide the chicken mixture evenly among the prepared ramekins.
Place a puff pastry sheet on a lightly floured surface, and roll out slightly to accommodate 3 large circles. Use a 5 1/2-inch round cutter to cut out 3 circles of puff pastry. Repeat with remaining puff pastry sheet. Using a pastry brush, paint the edges of each circle with the egg wash. Place each circle, egg wash side down onto the top of each ramekin, allowing the excess to hang over the edge of the ramekin. Press the excess pastry into the ramekin to seal. Place the ramekins on a baking sheet and bake for 20 to 25 minutes or until the pastry is golden brown and crispy. Remove from the oven and cool for 5 minutes before serving.
Yield: 6 servings