In a large frying pan, heat a tablespoon of oil over medium heat. Once hot, add the sliced large leeks and sauté for about 5 minutes until they become soft and translucent.

Next, incorporate cubed boneless chicken thighs and cook for an additional 5-7 minutes, stirring occasionally until the chicken is browned on all sides.

Reduce the heat to low and add 25g of butter to the pan, stirring until melted. Gradually sprinkle in 25g of plain flour, mixing to create a roux that cooks for about 1 minute.

Slowly pour in 300ml of chicken stock and 100ml of double cream, whisking constantly until the mixture thickens and becomes creamy—this should take about 3-5 minutes.

Season with salt and pepper to your taste.

Preheat your oven to 200°C (180°C Fan). Spoon the thick and creamy chicken and leek filling into a pie dish, spreading it evenly.

Carefully lay the ready-rolled puff pastry over the top, trimming any excess edges. Crimp the edges securely to seal in the goodness.

Make a small steam vent in the center to allow steam to escape during baking.

Brush the pastry generously with the beaten egg for a golden finish. Place the pie in the hot oven and bake for 25-30 minutes, or until the pastry is puffed up and beautifully golden brown.

Keep an eye on it, and remove from the oven when it's tempting with its aromatic scent and delightful color.