Classic Chicken Pot Pie with Flaky Butter Crust

Preheat the oven to 400°F (200°C) and set a rack in the middle position.

In a large skillet, melt the butter over medium heat until foaming, then add the onion, carrots, and celery with a pinch of salt; sweat 7-8 minutes until softened and the onions turn translucent.

Stir in the garlic and thyme and cook 1 minute until fragrant, then sprinkle the flour over top and cook 2 minutes, stirring constantly, until it looks pale and toasty.

Whisk in the chicken stock in a slow stream, followed by the milk, and simmer 4-5 minutes until the sauce is thick enough to coat a spoon.

Off the heat, stir in the shredded chicken, peas, a squeeze of lemon juice, 1 tsp salt, and plenty of black pepper; taste and adjust seasoning.

Transfer the filling to a 9-inch deep pie dish and let cool 10 minutes so the pastry doesn't melt on contact.

Roll the puff pastry to slightly larger than the dish, drape it over the filling, trim the overhang to ½ inch, and crimp against the rim; cut 3 small vents in the centre.

Brush all over with beaten egg for a lacquered finish, then bake 28-32 minutes until the pastry is deep golden brown and the filling bubbles up through the vents.

Rest 10 minutes before serving so the sauce sets slightly.