Crusty cheddar pies

This recipe is designed to be made ahead and frozen – a family-friendly batch pie, with cheesy mashed potato atop hidden broccoli, leeks and celery

500g slim young leek, thickly sliced

300g broccoli, cut into small florets

3 celery sticks, de-stringed and sliced

1½ kg floury potato, such as King Edward, cut into evensized chunks

85g butter

170g pot 0% fat Greek yogurt 850ml semi-skimmed milk 75g plain flour

2 tsp English mustard

1 tsp wholegrain mustard 300g pack mature cheddar, finely grated

Handful frozen peas

1 Bring a large pan of salted water to the boil. Put the leeks, broccoli and celery into a large steamer. Then add the potatoes to the water and cook for 20 minutes, with the vegetables steaming on top, until all are tender. Drain the potatoes, then mash with plenty of seasoning, 25g of the butter and all of the yogurt.

2 While the veg cooks, pour the milk into a pan, add the flour, both mustards and remaining butter, and cook over a medium heat, whisking all the time, until smooth and thickened. Stir in half the cheese and season. Remove from heat.

3 Divide the steamed veg and peas between eight individual pie dishes. Pour over the sauce and top with the mash, then sprinkle over the remaining cheese.

4 Pack into freezer bags and use within three months. To serve, unwrap and put the dishes on a baking tray in the cold oven, then set to 200C/180C fan/ gas 6. Bake for 5055 mins until bubbling and hot all the way through.