Leek, Cheese and Potato Pie

Based on a recipe from Nigel, this is hardly diet food, but it warms the cockles and used up lots of odds and ends from the fridge.  Cut a medium peeled potato into small cubes and steam until tender.  Meanwhile, gently sweat a couple of cleaned, sliced leeks in about 20g of butter until soft, but not browned.  Turn off the heat and allow a dessertspoon of creme fraiche to melt through the leeks.  Cool a little, then gently stir in the cooked potatoes, about 50g of strong cheddar cheese, and I added a couple of slices of ham that needed using up.  Season well with black pepper.  Unroll a sheet of ready-rolled puff pastry and place on a baking sheet.  Spread the cooled filling on one half, leaving a centimetre border around the edge.  Brush the exposed border with some milk and bring the other half of the pastry over, sealing the edges.  Make a steam-hole in the top of the pie, brush with more milk, and cook at around 170C for 30 minutes or so until lovely and brown and crisp.  Would serve 4 at a pinch we we devoured it between two.  But we are pigs, after all.