Ham, Turkey and Brussels Sprout Pie

Preheat the oven to 200C/180C fan/gas 6. Melt the butter in a large frying pan over medium heat, then cook the diced onion and celery for 8-10 minutes until softened but not browned.

Stir in the flour and cook for 1 minute, mixing well so the vegetables are evenly coated. Gradually pour in the stock, stirring constantly to prevent lumps, then simmer until the sauce thickens enough to coat the back of a spoon.

Add the cream, mustard, and grated cheese, stirring until the cheese melts into the sauce. Fold in the turkey or chicken, diced ham, and halved Brussels sprouts, then season with salt and black pepper to taste. Remove from the heat.

Spoon the filling into a baking dish. Unroll the shortcrust pastry and roll it slightly thinner if needed so it fully covers the dish.

Lay the pastry over the filling and seal the edges by pressing or crimping them against the rim of the dish. Lightly score the top into 6 portions and prick along the lines with a fork to let steam escape. Brush with milk or beaten egg, then scatter over the extra cheese.