1: Whack the oven on at 180C. Start by making the topping. Peel the sweet potatoes and cut into chunks, then place them in a large microwave safe bowl. Cover with a plate and microwave on full power for 15-20 minutes.

2: Meanwhile, peel and roughly chop the onion and garlic. Heat the vegetable oil in a large casserole dish, or deep frying pan, over a medium-high heat. Once hot, add the onion and garlic and cook for 4-5 minutes, stirring often, until softened.

3: Once cooked, add the tomato purée and cook for a couple more minutes, then add the tin of tomatoes and crumble in the stock cube, then bring it up to the boil so it’s bubbling. Drain the lentils into a sieve and rinse under the tap, before adding to the pan. Roughly slice up the mushrooms and add these in too, along with the frozen vegetables. Give it all a good stir, then reduce the heat so it’s bubbling gently at a simmer and cook for 15 minutes until the sauce has thickened.

4: Spoon it into an ovenproof dish and set aside.

5: Next, make the topping with the cooked sweet potatoes. Drain off any liquid from the potatoes and roughly mash them with a fork or masher. Spoon the sweet potato mash on top of the cottage pie filling.

6: Cook in the hot oven for 35-40 minutes, until golden brown and bubbling. Spoon onto plates and dig in.