01 - Preheat oven to 375°F (190°C). Lightly grease a 6-cup muffin tin.
02 - Flatten each sourdough bread slice using a rolling pin. Brush both sides with melted butter. Firmly press each slice into a prepared muffin cup to create a shell. Bake for 10 minutes, until lightly golden. Set aside.
03 - In a large skillet over medium heat, melt 2 tablespoons of butter. Add the finely chopped onion, diced carrots, and diced celery. Sauté for 5 minutes until the vegetables are softened.
04 - Sprinkle the all-purpose flour over the sautéed vegetables. Stir continuously for 1 minute to form a roux.
05 - Gradually whisk in the whole milk and low-sodium chicken broth. Continue stirring constantly until the mixture thickens to a sauce consistency, approximately 3 minutes.
06 - Stir in the pumpkin puree, pumpkin pie spice blend, dried thyme, garlic powder, kosher salt, and ground black pepper. Cook for 2 minutes, allowing the flavors to meld.
07 - Add the diced cooked chicken breast and frozen peas to the skillet. Stir until thoroughly combined and heated through. Remove the skillet from the heat.
08 - Spoon the prepared filling evenly into each of the pre-baked sourdough cups.
09 - If desired, sprinkle the tops with grated Parmesan cheese. Place the filled cups back into the oven and bake for 15–20 minutes, or until the tops are golden brown and the filling is bubbling.
10 - Allow the pot pie cups to cool for 5 minutes. Garnish with fresh chopped parsley before serving warm.