+To prepare the short pastry:
°280g Type 80 flour (type 55 or 65 works well too)
°100 grams of butter
+For the pie:
°2 chicken stock cubes
°1 onion
°3 celery sticks
°2 large carrots, depending on their size
°3 good sized sweet potatoes
°2 Nice chicken fillets (400 to 500 grams)
°25 grams of flour
°12 cl of milk
°chopped parsley
°1 egg

*Methods : 
+Preparing the short pastry:
In the bowl of the robot, pour the flour, a pinch of salt and the butter cut into pieces. Mix everything until you get a sandy mixture.
Continuing to mix, add a little water spoon by spoon until you get a soft ball of dough.
Leave it for an hour in the refrigerator.
Boil 40 cl of water and stir in 2 chicken stock cubes.
Finely chop the stalks of celery and onions.
Peel the carrots and potatoes and cut into cubes.
Cut the chicken fillet into pieces.
In  fry pan, heat a little oil.
Fry the onions over low heat.
Add the carrots and celery and cook 2 minutes, stirring often.
Pour in broth & bring to a boil.
Add the potatoes, reduce heat and cook for 10 minutes over low heat, stirring constantly.
In a frying pan, heat a little oil and brown the chicken pieces. Salt and Pepper.
Heat the milk for one minute in the microwave. Add the flour and stir with an electric mixer to avoid lumps.
Pour over vegetables as soon as they are cooked. Leave it on the fire, stirring, until the mixture thickens.
Remove from heat and add meat, salt, pepper and chopped parsley. Mix well.
Preheat oven to 220 (thermostat 7).
We take the dough out of the refrigerator and cut it in half.
Using a rolling pin, roll out the first half of the dough.
Cover the tart tray with butter paper and put the dough in the tray.
Pour the mixture of vegetables and chicken into the mold.
Roll out the rest of the dough on the work surface and put it on the pie.
Slide the edges of the second circle of dough along the edge of the pie pan (between the filling and the dough) and fold the edges of the first circle of dough over the second, pressing gently to adhere well. 
Make 4 slits in the top of the cake to allow air to escape.
In a small bowl, whisk the egg and spread it over the dough with a pastry brush.
If you have some dough left, you can cut out shapes to decorate the pie.
Bake for 15 minutes.
Lower the oven to 175 (thermostat 6) and cook for another 20 minutes.
Serve hot.

Enjoy !