Grease a pie dish and preheat oven to 180°C. Put flour into a bowl together with the cubed butter and on a slow speed mix until it resembles breadcrumbs. With the motor still running, add the water a little at a time until the pastry forms.
Wrap in clingwrap and chill in the fridge for half an hour.
Roll out on a floured surface and line the pie dish. Place in the fridge for 15 minutes.
Prick the bottom of the casing with a fork and bake blind for 10 minutes. Allow to cool before brushing with the eggwash and pop it back in the oven for 5 minutes. Cool before adding the filling.
Fry onion in butter until soft and golden.
Sprinkle half of the cheese onto the cooled base and add the cubed gammon and onion.
Whisk the eggs, cream and seasoning until combined and pour over. Sprinkle on the rest of the cheese.
Bake for 30 minutes until risen and golden. Reprinted with permission of Sous Chef. To see more recipes, click here.