1 large sweet potato, peeled and cut into 1cm cubes
150 ml whole milk
50g butter
2 tbsp chives, finely sliced
Salt and pepper to season
30g grated cheddar (optional)
Method
Heat the oven to 180c and bring a medium-large saucepan of water to the boil
Blitz the mushrooms in a food processor, or chop finely by hand, and mix with the beef mince
Heat a large sauté pan or casserole with olive oil and add the onion. Season and cook for a few minutes until softened. Add the beef and mushroom mix, turn the heat up a little and cook until the liquid has evaporated. Add the flour and stir well
Add the bay leaf, Worcestershire sauce and tomato purée and stir well. Add a splash of water if the mixture seems too dry. Cook for 5 minutes
Cook the celeriac and sweet potato in the boiling water for 10 minutes until soft then drain and return to the pan. Turn the heat back on and stir a little to cook away any excess liquid
Add the milk and butter to the pan, season well and start mashing with a potato masher. Once smooth, stir in the chives and turn off the heat
Put the beef and mushroom blend in an oven dish and spread the mash over the top. Use a fork to make lines in the mash and sprinkle over the cheese if using. Cook in the oven for about 25 minutes or until golden then serve