Step 1

To make the filling, heat the oil in a large, wide-based non-stick saucepan or sauté pan and gently fry the onion, celery and leek for 5 minutes, stirring regularly. Add the mushrooms and courgette and cook for a further 5 minutes, or until softened and lightly browned. Stir in the garlic and cook for a few seconds more.

Step 2

Add the carrots, tomatoes, drained lentils, 300ml/10fl oz water, wine (or extra water), tomato purée, yeast extract, mixed herbs and crumbled stock cube. Season with salt and pepper and bring to a gentle simmer.

Step 3

Cook for 30 minutes, or until thick. Stir occasionally at the beginning and more regularly towards the end of the cooking time so that it doesn’t stick. Add a little extra water if necessary; it should look nice and saucy, but thick enough to support the weight of the potatoes. Adjust the seasoning to taste, making sure you are generous with the black pepper.

Step 4

While the vegetables are simmering, make the mash. Put the potatoes in a large saucepan and cover with cold water. Bring to the boil, then reduce the heat slightly and cook for 15 minutes or until very soft.

Step 5

Preheat the oven to 200C/180C Fan/Gas 6.

Step 6

Drain the potatoes in a colander then return to the pan and mash with the almond milk, oil and nutritional yeast. Add a little more milk if necessary, so that the potatoes are really light and fluffy. Season with salt and pepper.

Step 7

Pour the lentil mixture carefully into a 2.5 litre/4½ pints ovenproof dish – a lasagne dish is ideal. Spoon the potatoes gently onto the filling and fluff up the surface with the back of a spoon.

Step 8

Bake for 30 minutes, or until pale golden-brown and bubbling. If the topping doesn’t go brown enough, pop under a hot grill for a couple of minutes. Serve hot.