Gather your ingredients.
Divide the pastry dough into two portions, with two-thirds in one and one-third in the other. Wrap the smaller portion in plastic wrap and set it aside.
Roll out the larger portion and line a shallow 1 1/2-quart baking dish (approximately 10x6 inches).
Gather the ingredients.
Create a roux by melting butter in a medium saucepan over medium-low heat. Add flour, salt, and pepper, stirring until smooth and bubbly. Cook for about 2 minutes, stirring constantly.
Gradually add chicken broth and half-and-half, cooking slowly until thickened while stirring constantly. Add the chicken and mix thoroughly.
Preheat your oven to 425°F.
Pour the creamed chicken mixture into the pastry-lined casserole dish.
Roll out the reserved one-third portion of pastry dough, ensuring it's large enough to cover the chicken mixture. Place it over the mixture, sealing the edges of the bottom and top crusts well. Create a slit in the middle of the top crust for steam to escape.
Bake for around 35 minutes or until the pastry achieves a lovely golden brown hue. Once done, remove it from the oven and let it cool for 10 minutes before serving. The filling will be piping hot. Enjoy it alongside a side salad and some crispy bread if you'd like.