There isn't a more comforting dinner than deep-dish chicken pot pie

Ingredients

For the crust

• 3 3/4 cups all-purpose flour (450 g)
• 3/4 teaspoon salt (3 g)
• 3 sticks cold unsalted butter, cubed (340 g)
• 3/4 cup ice water, plus more as needed (173 g)

For the filling and assembly

• 6 tablespoons unsalted butter, divided (85 g)
• 1 large sweet onion, diced (about 325 g)
• 3 stalks celery, diced (about 300 g)
• 3 carrots, diced (about 225 g)
• 3 cloves garlic, minced (15 g)
• 1 pinch salt and freshly ground black pepper, to taste
• 1/2 cup all-purpose flour (60 g)
• 4 cups (1 liter) chicken stock (907 g)
• 1 bay leaf
• 4 sprigs rosemary
• 4 sprigs thyme
• 1/4 cup heavy cream (60 mL)
• 4 cups chopped, cooked chicken (575 g)
• 1 1/3 cups frozen peas (200 g)
• 1 brush of egg wash, as needed for finishing

Directions

1. Preheat the oven to 400°F/205°C. Place a 9-in/23 cm springform pan on a baking sheet lined with parchment paper.
2. Make the pie crust: In a large bowl (working with a pastry cutter or your hands) or in the bowl of a food processor, combine the flour and salt. Add the butter and toss well to coat the cubes in flour. Cut the butter into the flour with your hands or a pastry cutter (or pulse it in the food processor), until the butter resembles the size of peas, and the mixture resembles a coarse meal. 
3. If mixing in the food processor, transfer the mixture to a large bowl. Make a well in the center of the bowl, add the water and mix until the dough comes together. It should be rough in texture, but hold completely together — it should not be sticky. If it's too dry/appears powdery, add more water 1 tablespoon (15 g) at a time until the dough comes together.
4. Divide the dough — you'll need about 2/3 of the dough for the bottom crust and about 1/3 for the top crust. Form each piece into a disk, wrap each piece of dough, and chill for at least 1 hour in the refrigerator (and up to 2 days).
5. While the crust is chilling, make the filling: in a large pot, heat 2 tablespoons (28 g) of butter over medium heat. Add the onions, celery, and carrot and sweat until the onions are translucent, 5 to 6 minutes. Add the garlic and sauté until fragrant, 1 minute more. 
6. Add the remaining 4 tablespoons (56 g) butter over medium heat. Once melted, whisk in the flour. Cook, stirring constantly, until the mixture is just starting to turn golden brown, 2 to 3 minutes. Gradually whisk in the chicken broth. Bring the mixture to a simmer. Add the vegetables back to the pot, along with the bay leaf, rosemary, and thyme. Simmer, stirring occasionally to prevent scorching, for 15 minutes.
7. Stir in the cream, chicken, and peas and return to a simmer. Simmer for 4 to 5 minutes more. Remove the mixture from the heat. Cool completely (this mixture can be made up to 2 days ahead and stored in the refrigerator until ready to assemble and bake). 
8. Par-bake the bottom crust: on a lightly floured surface, roll out the larger quantity of dough to 1/4 in/6 mm thick. Transfer it to the springform and trim the edge so there is 1/2 in/1 cm overhang all around the edge of the pan. Chill the dough inside the pan for at least 30 minutes in the refrigerator.
9. Dock the chilled dough with a fork on the base and sides. Line the crust with parchment paper and pie weights, and bake until the crust is beginning to brown at the edges, 15 to 17 minutes. Remove the parchment and pie weights, and return the pie to the oven for 2-3 minutes more, until the base appears dry. While the crust is still warm, use scissors to cut away any excess crust that's still hanging over the edge of the pan. Cool the crust to room temperature. 
10. Mound the cooled filling into the cooled crust, pressing firmly to ensure minimal air pockets. Make a nice, rounded mound at the top. On a lightly floured surface, roll out the smaller amount of dough to 1/4 in/6 mm thick. Use a rolling pin to transfer the dough to the top of the pie.
11. Trim away any excess dough, leaving about 1/2 in/1 cm excess all the way around the edge. Nudge the edge down into the side of the springform pan so that it meets the top edge of the bottom crust. Push the crust down a bit so the excess puckers outward and creates a little lip, just like the edge of a typical pie. Press that outer lip together to seal the edges a bit, then crimp with a fork to seal.
12. Egg-wash the top crust evenly and cut vents into the top crust. Transfer the pie to the prepared baking sheet and bake until the crust is very golden and the filling is bubbling through the vents, 50-60 minutes. If the pie is browning too much or too quickly, reduce the oven temperature to 375°F/190°C and/or tent the top of the pie with foil for the remainder of bake time.
13. Cool the pie for 20-30 minutes before slicing and serving. Un-mold the outer edge of the springform pan. Slide an offset spatula around the edge of the base of the pan; if the pie is really cool and it feels solid in the middle, you'll likely be able to pick up the pie with your hands (or a large spatula) and transfer to a platter or stand. If it feels soft in the middle, you may rather keep it on the springform base for slicing.