Prepare the Pastry Base :Preheat your oven to 180°C (350°F). Line a 9-inch tart tin with the shortcrust pastry sheets, pressing them gently to form a smooth base. Trim any overhanging edges, prick the base with a fork, and bake for 10 minutes or until lightly golden. Remove from oven and set aside.

Cook the Bacon and Onion : In a frying pan, cook the chopped bacon over medium heat until crispy. Add the sliced onion and crushed garlic, cooking until the onion is soft and translucent. Set aside to cool.

Prepare the Chicken Filling : In a small saucepan, melt the butter over medium heat. Stir in the flour, cooking for 1-2 minutes until smooth and bubbling. Gradually whisk in the milk, cream, chicken stock powder, and paprika, stirring until the mixture is thick and creamy.

Combine Ingredients : In a large bowl, whisk together the whole egg, egg yolks, and creamy sauce until smooth. Add the chopped barbecue chicken, bacon mixture, parsley, and chives, mixing until well combined.

Assemble the Tart : Pour the chicken mixture into the prepared pastry shell, spreading it evenly.

Bake the Tart : Bake in the preheated oven for 25-30 minutes or until the filling is set and the top is golden brown.

Serve and Enjoy : Garnish with extra chives if desired, and serve warm. This Chicken Lorraine Tart pairs beautifully with a fresh side salad.