In a large skillet, heat the olive oil over medium heat. Once hot, add the sliced leeks and cook until soft, about 4–5 minutes.

Next, add the sliced mushrooms, cooking for an additional 3–4 minutes until they’re tender and lightly browned.

Stir in the shredded cooked chicken, then pour in the cream. Season with salt and pepper to taste. Allow the mixture to simmer on low heat for about 5–7 minutes until it thickens slightly.

Preheat your oven to 200°C (390°F). Roll out the puff pastry on a lightly floured surface to fit your pie dish.

Pour the creamy chicken mixture into the base of the pie dish. Place the rolled-out puff pastry on top, pressing the edges to seal. Cut a few slits in the top of the pastry for steam to escape. Brush with beaten egg to give it a golden color when baked.

Place the pie in the oven and bake for 25–30 minutes, or until the pastry is puffed and golden brown.

Once it’s out of the oven, allow it to cool for a few minutes before serving.