In a large bowl, combine your flour and salt. Add in your butter and stir until it is a coarse texture. Slowly pour in your water until the dough is sticky.
Slowly pour in the water, a tablespoon at a time, until the dough sticks together. Turn out onto a clean surface and wrap in clingfilm. Place in the fridge for a minimum of 30 minutes. Remove form fridge and roll until it is about an inch thick.
While the crust is chilling you can make the filling. Pour your oil into a large pot and gently cook your chicken on a medium temperature for about 4 minutes. Add the carrots, peas, onions and salt.
Stir in the condensed cream of chicken into the pot and combine with the vegetable and chicken. Leave to simmer for about 30 minutes. Season with salt if necessary.
Preheat oven 200°C to gas mark 6.
Pour the chicken filling into an ovenproof dish and lay the dough on top. Press down with a fork.
Lightly coat the crust with butter.
Place in the oven for about 25 minutes or until the pastry is golden and the filling is bubbling.
Allow to cool for five minutes before serving.