1-Season the chicken breasts with salt and pepper, then place them in a saucepan, cover with water, and simmer until just cooked through. Once done, remove the chicken, let it cool, and chop it into bite-sized pieces. Reserve about 1 ¾ cups of the cooking water for later use.

2-In the same saucepan, cook the onions and celery in butter until they become soft and translucent. Stir in the flour, salt, pepper, garlic powder, bouillon paste, and celery seed to build the base of your sauce.

3-Slowly add the reserved cooking water and 1 cup of milk, then simmer the mixture until it thickens into a creamy filling. This step is crucial to get that perfect consistency that holds everything together.

4-Mix in the chopped chicken and frozen vegetables, then adjust the seasoning if needed. Let the filling cool before moving on to ensure it sets properly when baked.

5-Preheat your oven to 425°F. Roll out one piece of the chilled pie crust dough and fit it into a 9-inch pie pan, then fill it with the cooled chicken mixture.

6-Roll out the second piece of dough to cover the filling, seal the edges, and crimp them for a nice finish. Cut small slits in the top to let steam escape during baking.

7-Beat the egg and mix it with 1 tablespoon of milk, then brush this over the top crust for a golden shine. Now, it’s ready for the oven.

8-Bake for 40-50 minutes until the crust turns golden brown and the filling bubbles. If the crust starts browning too fast, cover it loosely with foil to protect it.

9-Let the pie rest for 15-20 minutes after baking to allow the filling to set, making it easier to slice and serve.