Step 1

To make the filling, heat the butter or oil in a large saucepan and gently fry the onion, carrots, celery and garlic for 15 mins until soft and golden. Turn up the heat, add the mushrooms, then cook for 3-4 mins. Sprinkle in the thyme and add the lentils. Pour over the wine and stock, then simmer gently, uncovered, for about 40-45 mins until the lentils are soft. If you find the mixture is drying out, you can add a splash more stock or water.

Step 2

Meanwhile, put the potatoes in a large pan, pour over boiling water and boil for 15-20 mins until tender. Drain well. You can use a potato ricer at this stage to make them super creamy, or mash with the butter and milk, then season with salt and pepper.

Step 3

Remove the lentils from the heat, add the tomato purée and yeast extract, if using. Stir well and check to see if you need seasoning, then add a good grinding of black pepper.

Step 4

Heat oven to 200C/180C fan/gas To assemble, butter four-six small pie dishes or one a large dish and spoon in the lentil mixture, then top with mash. It’s fun to pipe on the mash if you have a piping bag, but if not, you can spoon it on and fluff into peaks with a fork. Bake for 30-40 mins until golden. Serve with peas on the side, if you like.