Potato, leek and cheese pie
This is made possible by BBC Foods! Ingredients For the flaky pastry 125g/4½oz butter, frozen for 1 hour 125g/4½oz hard vegetable fat, such as Trex, frozen for 1 hour 350g/12oz plain flour, plus extra for dusting 1 free-range egg, beaten for egg wash For the pie filling 60g/2¼oz butter 2 small leeks, thinly sliced 1 onion, thinly sliced 450g/1lb potatoes, cut into…