1. Preheat the Oven
Preheat your oven to 200°C (180°C fan)/400°F/gas mark 6.
2. Cook the Chicken and Vegetables
- Heat the Olive Oil: In a large frying pan or skillet, heat the olive oil over medium heat.
- Add the Chicken: Add the diced chicken and cook for 5-7 minutes until golden brown and cooked through. Remove the chicken from the pan and set it aside.
- Cook the Vegetables: In the same pan, add the leeks, carrots, and garlic, cooking for 5 minutes until softened.
3. Make the Creamy Sauce
- Add the Crème Fraîche and Stock: Stir in the crème fraîche, chicken stock, and Dijon mustard, mixing well. Let the sauce simmer for 3-4 minutes until it starts to thicken.
- Season the Sauce: Add the thyme, and season with salt and pepper to taste.
- Return the Chicken: Add the cooked chicken back into the pan, stirring to combine everything evenly. Let the mixture cook for another 2 minutes, then remove from heat.
4. Assemble the Pie
- Fill the Pie Dish: Pour the chicken and vegetable filling into an ovenproof pie dish, spreading it out evenly.
- Top with Puff Pastry: Roll out the puff pastry if necessary and place it over the top of the filling, pressing the edges down around the dish to seal it. Trim any excess pastry.
- Brush with Egg: Brush the top of the pastry with the beaten egg to help it turn golden brown in the oven.
5. Bake the Pie
Place the pie in the preheated oven and bake for 25-30 minutes, or until the pastry is puffed up and golden brown.
6. Cool and Serve
Allow the pie to cool for a few minutes before serving. Enjoy it warm with a side salad or steamed vegetables.