Preheat your oven to 375°F and set aside the store-bought pie crust to bring it to room temperature, ensuring it's perfectly pliable when it's time to work with it.
Begin by dicing the chicken breast and cooking it in a splash of avocado oil or olive oil. Season with salt and pepper to enhance its flavor. Once the chicken is fully cooked, set it aside in a dish for later.
In a skillet, sauté the finely chopped onion, celery, potato, and carrots until the onions turn translucent.
Add the cream of mushroom soup to the skillet, stirring gently over low heat for about 3 minutes. Sprinkle in the dried thyme.
Now, it's time to add the frozen peas and the previously cooked chicken to the mixture. Stir everything together, allowing the flavors to meld.
If your skillet is oven-safe, carefully place the store-bought pie crust on top of the mixture. Press the edges with a fork. Alternatively, transfer the entire mixture into a pie dish before adding the pie crust on top.
Lightly brush the pie crust with a beaten egg wash.
Bake the pot pie in the preheated oven until the crust achieves a beautiful golden brown color, usually around 30-35 minutes.
Once done, remove it from the oven and allow it to cool for 7-10 minutes before serving.