Preheat your oven to 400°F (200°C).

In a large pot, cook your chicken until tender, about 15-20 minutes. Drain and shred the chicken.

Add diced bacon to the pot and sauté until crispy, about 5-7 minutes. Then, add chopped leeks and mixed vegetables, cooking until softened, about 5 minutes.

Stir in the cream and herbs, mixing well, then let simmer for about 3-5 minutes.

Roll out your pastry on a floured surface until about 1/8 inch thick and line a baking dish with it.

Spoon the creamy chicken and vegetable mixture into the pastry-lined dish, leveling it off.

Cover with another piece of pastry, sealing the edges and creating slits on top for steam.

Brush the top with beaten egg and bake for 30-40 minutes or until golden brown.

Allow to cool for about 10 minutes before serving.