Preheat your oven to 425°F (220°C).

In a large pot, melt the butter over medium heat. Toss in the diced onions, carrots, and mushrooms, and sauté until softened, about 5–7 minutes.

Add the minced garlic and cook for another minute until fragrant.

Sprinkle the flour over the vegetable mixture and stir until well combined. Gradually pour in the chicken stock and heavy cream, stirring continuously until the mixture thickens.

Stir in the cooked chicken, frozen peas, chopped parsley, sea salt, and black pepper. Mix until evenly combined and remove from heat.

Roll out the pie crust and place it in a pie dish. Pour in the creamy chicken mixture.

Cover with a second crust, sealing the edges well. Don’t forget to cut slits in the top to allow steam to escape!

Beat the egg and brush it over the top crust for a lovely golden color when baked.

Bake in the preheated oven for 30-35 minutes, or until the crust is golden brown and bubbly.

Allow the pie to cool slightly before serving — this will help avoid burning your mouth!