Preheat the oven to 390⁰F. Chop the onion and garlic. Cut the leek in thin half rings and cut the chicken thighs in bitesize pieces. Melt the butter in a deep frying pan. Brown the chicken pieces in the pan. Add the onion, garlic and leek and bake for a couple of minutes. Add salt and pepper to taste.

Add the flour to the frying pan and mix everything together. Next, add little by little the milk, while you keep stirring the mixture. When all the milk is added also the stock cube, the peas and the parsley can be added. Again season with salt and pepper. Let everything simmer for a couple of minutes until the sauce has thickened.

Transfer the mixture into a greased oven dish and cover with the puff pastry. Whisk the egg in a small bowl and brush the puff pastry with the egg. Carve small notches in the pastry. Bake the pie in approx. 20 minutes until the puff pastry is brown and cooked.