Prepare the dough by combining flour, salt, and sugar in a bowl.
Add butter cubes and mix until crumbly, then gradually add water until dough forms.
Refrigerate for 1 hour.
Preheat your oven to 400°F.
Roll out half of the dough and place it in the bottom of a pie dish.
In a large saucepan, heat olive oil over medium heat.
Add chicken pieces and cook until lightly browned.
Remove and set aside.
Saute onions, carrots, and celery in the same pan until tender.
Add chicken stock and return the chicken to the pan.
Simmer for about 30 minutes.
Pour the filling into the prepared pie dish.
Cover with the remaining rolled-out dough, sealing the edges.
Make slits on top to allow steam to escape.
Bake for about 45 minutes or until golden brown.