Preheat the Oven : Preheat your oven to 400°F (200°C).

Cook the Vegetables : In a medium saucepan, combine the chicken broth, potatoes, celery, carrot, and onion. Bring to a boil, then reduce heat to medium-low and simmer for 10 minutes, or until the vegetables are tender. Stir in the frozen peas and cooked chicken. Remove from heat.

Make the Sauce : In a separate skillet, melt the butter over medium heat. Whisk in the flour to create a roux and cook for 1–2 minutes. Gradually whisk in the milk and 1 cup of the reserved chicken broth from the vegetables. Stir continuously until thickened and creamy.

Combine Filling Ingredients : Add the creamy sauce to the chicken and vegetable mixture. Stir in the sage, nutmeg, and season with salt and pepper to taste. Mix well and let cool slightly.

Assemble the Pot Pie : Place one pie crust into a 9-inch pie dish, pressing it gently into the dish. Pour the filling into the crust, spreading it evenly. Cover with the second pie crust, trimming any excess dough, and crimp the edges to seal. Cut a few small slits in the top crust to allow steam to escape.

Bake : Place the pie on a baking sheet to catch any drips and bake in the preheated oven for 30–35 minutes, or until the crust is golden brown.

Cool and Serve : Let the pie cool for 5–10 minutes before slicing. Serve warm and enjoy!