Pure British comfort food made easy! A rich, creamy filling of chicken, cremini mushrooms, and herbs tucked beneath a buttery sheet of puff pastry or shortcrust dough. No soggy bottom, just pure comfort in every bite.
Heat 2 tablespoons olive oil and 2 tablespoons butter in a large, non-stick, high-sided frying pan or Dutch oven over medium-high heat. Season the chicken pieces evenly with a sprinkle of salt and pepper. When the butter is melted and bubbly, add the chicken to the pan. Cook until no longer pink on the outside (it will finish cooking in the oven). Remove the chicken with tongs or a slotted spoon to a plate or bowl and set aside, leaving any remaining fat in the pan.
Cook the Mushrooms and Onion:
Add the remaining 2 tablespoons of oil and 2 tablespoons of butter over medium heat. When the butter is melted and bubbly, add the mushrooms. Cook without moving them too much at first, then add the onions. Stir often until the onions are softened and the mushrooms have reduced in size. Sprinkle with a little salt and pepper.
(Tip: Don’t salt the mushrooms before cooking, or they can release too much moisture.)
Make the Sauce Base:
Lower the heat and sprinkle the flour evenly over the mushroom and onion mixture. Stir constantly for 1 to 2 minutes to cook out the raw flour taste. Stir in the thyme and return the cooked chicken to the pan.
Thicken:
Slowly pour in the chicken stock and milk while whisking continuously to prevent lumps. Bring to a gentle simmer until it thickens into a glossy gravy. Taste and adjust with extra salt, pepper, or thyme if needed. (Tip: You can prepare the filling up to this stage a day ahead. Transfer to a sealed container and refrigerate.)
Preheat your oven to 400°F / 200°C (180°C Fan for UK fan-assisted ovens). Lightly grease the pie pan using the extra butter.
Assemble the Pie:
Transfer the chicken and mushroom filling into a deep 9-inch (23 cm) pie dish or deep baking dish. Brush a little water or milk on the edge of the pie dish to help the pastry stick. Roll out the shortcrust pastry to fit (or drape the sheet of puff pastry) right over the top of the dish. Trim the edges, leaving a small overhang, and crimp or press firmly against the rim to seal. Cut two small slits in the center for steam to escape.
Brush the pastry generously with the egg wash. Bake for 25 to 30 minutes until the crust is puffed and golden brown.