Follow these detailed steps to ensure your Mini Chicken Pot Pie Muffins turn out perfectly every single time. We will first create the rich filling and then assemble our individual pies for baking.

1. Prepare the Oven and Muffin Tin: Begin by preheating your oven to 400°F (200°C). This is a crucial first step, as a hot oven ensures the pie crust starts baking immediately, preventing a soggy bottom. Generously grease a standard 12-cup muffin tin with non-stick cooking spray or by wiping it with butter. This will guarantee your mini pies release easily after baking.
2. Sauté the Aromatics: In a large skillet or saucepan, melt the 3 tablespoons of unsalted butter over medium heat. Once the butter is melted and begins to shimmer, add the finely diced yellow onion. Sauté the onion, stirring occasionally, for about 3-4 minutes. You are looking for the onion to become soft, translucent, and fragrant, but not browned. This process sweetens the onion and builds the first layer of flavor for our filling.
3. Create the Roux and Sauce Base: Sprinkle the ¼ cup of all-purpose flour over the softened onions in the skillet. Stir continuously for about one minute until the flour is fully incorporated with the butter and onion. This step, known as making a roux, is essential for thickening the sauce. Toasting the flour for a minute cooks out any raw, pasty flavor.
4. Build the Creamy Sauce: While stirring or whisking constantly to prevent lumps, slowly pour in the 1 cup of chicken broth. The mixture will begin to thicken almost immediately. Once the broth is incorporated, slowly whisk in the ½ cup of heavy cream. Continue to cook, stirring frequently, until the sauce is smooth, bubbly, and has thickened enough to coat the back of a spoon. This should take about 3-5 minutes.
5. Combine the Filling Ingredients: Turn the heat down to low. To the thickened sauce, add the 2 cups of cooked chicken, the 1 ½ cups of thawed mixed vegetables, the ½ teaspoon of dried thyme, and a generous pinch of salt and black pepper. Stir everything together until the chicken and vegetables are evenly coated in the creamy sauce. Let it simmer gently for another minute for the flavors to meld. Remove the skillet from the heat and set it aside to cool slightly while you prepare the crusts.
6. Prepare the Pie Crusts: Unroll the two refrigerated pie crusts onto a lightly floured surface to prevent sticking. Using a 4-inch round cookie cutter or the rim of a wide-mouthed glass, cut out 12 circles from the dough. You may need to gently re-roll the scraps to get all 12 circles.
7. Assemble the Mini Pies: Carefully press each of the 12 dough circles into the cups of your prepared muffin tin. Gently guide the dough down to line the bottom and up the sides of each cup, creating a small pie shell. A small tart tamper or the back of a spoon can be helpful here.
8. Fill the Pies: Spoon the slightly cooled chicken pot pie filling evenly into each of the 12 pie crust shells. Be careful not to overfill them; fill them just to the top of the crust’s edge. Overfilling can cause the filling to bubble over and make a mess in your oven.
9. Add the Top Crust (Optional but Recommended): If you want a full “lid” on your pot pies, you can use the dough scraps to cut out smaller, 1.5 to 2-inch circles or decorative shapes (like leaves or stars) to place on top of the filling. Alternatively, you can leave them open-faced for a rustic look.
10. Apply the Egg Wash: In a small bowl, whisk together the large egg and 1 tablespoon of water to create an egg wash. Using a pastry brush, lightly brush the tops of the exposed crust edges (and the top crusts, if you added them). This step is the secret to a shiny, beautifully golden-brown finish.
11. Bake to Perfection: Place the muffin tin on a baking sheet to catch any potential drips. Bake in the preheated 400°F (200°C) oven for 20-25 minutes. The pies are done when the filling is hot and bubbly and the crust is a deep golden brown.
12. Rest and Serve: Remove the muffin tin from the oven and let the mini pot pies rest in the tin for at least 5-10 minutes. This is a critical step that allows the filling to set up slightly and the pies to firm up, making them much easier to remove without falling apart. Carefully run a thin knife around the edge of each muffin to loosen, then gently lift them out. Serve warm and enjoy!