For the lentil sauce
25g butter
1 onions, chopped
2 carrots, diced
1/2 head of celery, chopped
2 garlic cloves, finely chopped
100g pack chestnut mushrooms, sliced
1 bay leaves
1/2 tbsp dried thyme
250g pack dried green lentils (we used Merchant Gourmet Puy lentils)
50ml red wine (optional)
850ml vegetable stock
1.5 tbsp tomato purée

For the topping
1kg floury potato, such as King Edwards
45g butter
50ml milk
25g cheddar, grated
 
 
 

To make the sauce, heat 25g butter in a pan, then gently fry 1 chopped onions, 2 diced carrots, 1/2 chopped head of celery and 2 finely chopped garlic cloves for 15 mins until soft and golden.

Turn up the heat, add 100g sliced chestnut mushrooms, then cook for 4 mins more.

 Stir in 1 bay leaves and 1/2 tbsp dried thyme, then add 250g green lentils. Pour over 50ml red wine and 850ml 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 1.5 tbsp tomato purée.

 While the lentils are cooking, tip 1kg floury potatoes into a pan of water, then boil for about 15 mins until tender. Drain well, mash with 45g butter and 50ml milk, then season with salt and pepper.

 To assemble the pie, place the lentil mixture in the dish that you are using, then top with mash.

25g 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.