Preheat your oven to 220°C/200°C fan/gas mark 7. Bring a large saucepan of water to the boil with 1/2 tsp salt.

Chop the potatoes into 2cm chunks (peel first if you prefer).

Add the potatoes to the pan of boiling water and cook until you can easily slip a knife through, 15-20 mins.

Meanwhile, halve any large cauliflower florets and pop them onto a large baking tray.

Drizzle with oil, sprinkle over the ground cumin, then season with salt and pepper. Toss to coat, then spread out in a single layer.

When the oven is hot, roast on the top shelf until golden brown and tender, 15-20 mins. Turn halfway through.

While the cauli roasts, thinly slice the mushrooms. Heat a drizzle of oil in a large frying pan on medium-high heat.

Once hot, add the mushrooms and season with salt and pepper. Cook until browned, 5-6 mins.

Meanwhile, peel and grate the garlic (or use a garlic press). Drain and rinse the lentils in a sieve. 

Grate the Cheddar. Roughly chop the chives (use scissors if easier).

Once the mushrooms are browned, add the garlic and harissa paste (add less if you don't like heat). Stir together and cook for 1 min.

Stir in the chopped tomatoes, lentils, veg stock paste and water for the sauce (see pantry for amount).

Bring to the boil, then lower the heat and simmer until thickened, 8-10 mins. Add a splash of water if it's a little thick. 

Once the potatoes are cooked, drain in a colander and return to the pan, off the heat.

Add a knob of butter and a splash of milk (if you have any) and mash until smooth. Season with salt and pepper, then stir through half the chives.

Once roasted, remove the cauliflower from the oven and turn your grill on to high.

Stir the cauliflower through the sauce, season with salt and pepper then transfer it to an appropriately-sized ovenproof dish. 

Top your pie filling with an even layer of mash and sprinkle over the cheese. Grill until golden and bubbling, 5-6 mins.

When ready, sprinkle the remaining chives over the pie to finish.

Enjoy!