Add the butter to a 5-quart Dutch oven or pot over medium to medium heat. Once it’s mostly melted, add the onion, carrot, and celery, and cook until the vegetables are softened but not browned, about 8 to 10 minutes, stirring occasionally. Add the garlic and cook 1 minute, stirring constantly.

Add the wine and use a wooden spoon to scrape up anything sticking to the bottom (that’s where the flavor is!). Cook until the wine is evaporated off, about 1 to 2 minutes.

Stir in the flour and cook 1 minute, continuing to stir constantly. Add the chicken stock and bring to a boil, stirring constantly.

Remove from the heat and stir in the cream, chicken, peas, thyme, sage, Worcestershire, salt, and black pepper.

Let the chicken pot pie filling cool to room temperature, about 2 hours.

Whisk together the flour and salt in a large bowl. Cut in the butter with a fork, a pastry cutter, 2 butter knives, or your fingertips. It should look crumbly, with some pieces of butter the size of small peas.

Drizzle the water in a little at a time, mixing as you go (you can use a fork to mix, but it works best mixing with your fingertips). Add just enough water so it comes together to form a ball of dough (you may need more or less water).

Divide the dough into 2 equal parts. Roll each into a ball, flatten each ball slightly into a disk, wrap them in plastic wrap, and refrigerate until chilled, about 30 minutes.

Lightly brush the wells of a muffin pan with butter.

Place 1 disk of dough onto a floured work surface. Working from the center out, roll the dough out to a rectangle about 3 to 4 mm thick (about 1/8-inch).

To make the pies in a regular muffin pan, you will need 14 (5-inch) circles to get pressed into the muffin wells, and 14 (3-inch) circles for topping. Stamp out as many as you can, and then repeat this process with the second ball of dough. Gather the dough scraps, re-roll the dough, and stamp out more if needed.

Gently press each 5-inch circle of dough into a muffin well in a muffin pan. If you’re using a standard-sized muffin pan, the dough should come up over the top a little, which is perfect. Use a fork to poke a few holes in the bottom crust of each tart.

Fill each muffin well to the top with chicken pot pie filling (about 3 tablespoons per pie), making sure the filling is compact and there are no air bubbles.

Lightly brush the top ring of dough with egg wash. Place 1 (3-inch) dough circle on top of each pie. Gently crimp the outside with a fork. Lightly brush each dough circle with egg wash, discarding any extra egg wash.