Preheat your oven to 220°C and put a large saucepan of water with 1/2 tsp of salt on to boil for the potatoes. Chop the mushrooms into roughly 1cm pieces. Peel or grate the garlic (or use a garlic press). Chop both types of potato into roughly 2cm cubes (no need to peel).

Heat a drizzle of oil in a large frying pan on medium high heat and add the mince. Season with salt and pepper. Break it up with a wooden spoon and cook until browned, 4-5 mins. Add the garlic and mushrooms and cook until browned, 4-5 mins more, stirring occasionally.

Meanwhile, add both types of potato to your pan of boiling water and simmer until tender, 15-20 mins. Tip: The potato is cooked when you can easily slip a knife through. Once cooked, drain in a colander and return to the pan. Add a large knob of butter and a splash of milk too (if you have some), season with salt and some pepper. Mash until smooth.

Once the mushrooms have browned, add the Worcester sauce to the pan and bubble away until evaporated, 1-2 mins. Add the sun-dried tomato paste, tomato passata, water (see ingredients for amount) and beef stock paste. Bring to the boil, then reduce the heat and simmer until thickened, 15-20 mins. 

Preheat your grill to medium-high. Transfer the cooked sauce to an ovenproof dish, spread the mash on top and grate over the cheddar cheese. Place under the grill and cook until golden, 10-15 mins.

There's time to put your feet up whilst the pie is in the oven. Once it's bubbling and golden brown on top, serve the sweet potato cottage pie on plates and tuck in!