To make the pastry, place the flour, salt, pepper and butter in the bowl of a food processor fitted with the metal blade. Pulse 5 times. Add the lemon juice and water and turn on the machine for 3 seconds. Using your hands, scrape the dough onto a floured surface and work it together into a smooth ball. Cover with parchment paper or plastic wrap and chill for 30 minutes.

Preheat the oven to 375 degrees.

To cook chicken: bring a large pot of water to a boil and add chicken breasts. Simmer for 7-8 minutes. Drain. Save the pot for later use. When chicken is cool enough to handle, cut into bite-size pieces and add back to pot. It is fine if the chicken is not cooked all the way through. Set aside.

Heat butter in a large skillet over medium heat. Add onion and carrot and sauté until onion is translucent. Add the flour and sauté for 3 minutes over medium-low heat, stirring constantly. Add the salt and paprika. Mix well. Add the chicken stock gradually while stirring and bring to a boil. Stir in the Worcestershire sauce. Taste the mixture for seasoning and add extra salt and pepper if needed.

Add peas, parsley and onion-carrot mixture to chicken in the pot and combine well. Transfer to a 13 x 9–inch casserole dish.

Roll out the pastry dough 1-inch larger than the area of the casserole dish. Cut hearts from the dough with cookie cutter, if desired, otherwise make a few small slits in the dough for steam to escape. Place the dough on top of the filling and crimp the edges.

Beat the egg yolk with the cream and brush the top of the pastry with the mixture. Place dish on top of a baking sheet and bake for 50-60 minutes or until golden brown.