Heat oven to 200C/180C fan/gas 6. In a large frying pan, soften the onion and celery in the butter for about 10 mins. Stir the flour into the veg until completely absorbed, then gradually stir in the stock. Simmer to a sauce consistency, then stir in the cream, mustard and cheese, followed by the turkey or chicken, ham and brussels sprouts. Take off the heat and season well.

Tip the pie filling into a baking dish. Unroll the shortcrust pastry and, if you need to, roll a little thinner until it’s big enough to cover the pie dish. Divide the pastry into 6 portions by pricking lines with the prongs of a fork. These pricked lines will also work as air holes for the steam to escape, so you don’t need to use a pie funnel. Lift the pastry onto the pie dish. Crimp or pinch the edges to seal the pastry to the dish, and glaze the top with a little milk or egg. Scatter with the extra cheese and bake for 30-40 mins until golden and crisp.

Leave the pie to cool for 5-10 mins, then serve with mash and greens, if you like.