To make the sauce, heat 50g butter in a pan, then gently fry 2 chopped onions, 4 diced carrots, 1 chopped head of celery and 4 finely chopped garlic cloves for 15 mins until soft and golden.

Turn up the heat, add 200g sliced chestnut mushrooms, then cook for 4 mins more.

Stir in 2 bay leaves and 1 tbsp dried thyme, then add 500g green lentils. Pour over 100ml red wine and 1.7l vegetable stock – it’s important that you do not season with salt at this stage.

Simmer for 40-50 mins until the lentils are very soft.

Season to taste, take off heat, then stir in 3 tbsp tomato purée.

While the lentils are cooking, tip 2kg floury potatoes into a pan of water, then boil for about 15 mins until tender. Drain well, mash with 85g butter and 100ml milk, then season with salt and pepper.

To assemble the pies, divide the lentil mixture between all the dishes that you are using, then top with mash.

Scatter over 50g grated cheddar and freeze for up to two months or if eating that day, heat oven to 190C/fan 170C/gas 5, then bake for 30 mins until the topping is golden.