In a Dutch oven, melt 4 tablespoons of unsalted butter over medium heat. Add 1 chopped onion and 2 diced carrots, stirring occasionally for about 8 minutes until softened. Toss in 8 ounces of sliced mushrooms and 2 minced garlic cloves, cooking for an additional 5 minutes until everything is tender and fragrant.

Sprinkle in 1/3 cup of all-purpose flour, stirring constantly for about 2 minutes to remove the raw flavor. Gradually pour in 2 cups of chicken stock and 1 cup of heavy cream, whisking until the mixture starts to thicken, which should take around 5 minutes.

Stir in 2 cups of shredded chicken, 1 cup of frozen peas, and ¼ cup of chopped fresh parsley until well combined. Season with sea salt and black pepper to taste.

Roll out one pie crust on a lightly floured surface into a circle, about 12 inches in diameter. Carefully place it into a deep pie dish, allowing the edges to hang over. Pour the chicken filling into the crust, then roll out the second crust and place it over the top.

Preheat your oven to 425°F (220°C) and brush the top crust with a beaten egg for a golden finish. Bake in the preheated oven for 30-35 minutes, or until the crust is golden brown and bubbling.

Once baked, remove the Chicken Pot Pie from the oven and let it cool for about 15 minutes. Serve warm.