Cheesy Marmite Mushroom Pie

For the pastry, take the puff out of the fridge 30 mins before starting and finely chop the chives. Roll out of the packet onto a lightly floured surface and drizzle with Marmite. Scatter over the cheese and the chives, then fold the two short ends of the pastry into the middle, then fold everything in half, like a book. Then fold the whole thing in half again before wrapping in cling film and popping back in the fridge for 30 minutes. This pastry isn't suitable for making the day before because of the added elements, so don’t be tempted to try it!

Start by tearing or chopping the mushrooms into equal-sized pieces. Heat a good glug of oil over high heat in a large, ovenproof frying pan and add the mushrooms, cooking until deeply golden – you will need to do this in batches so as not to overcrowd the pan. Once cooked, remove from the pan and set aside. Halve and finely slice the onion, then finely chop the garlic.

Reduce the heat to medium, and add more oil to the pan, before frying the onion, garlic and thyme for around 5 mins. Add the tomato purée and cook for 2 mins, then pour in the stout. Simmer for 5 mins, then add the mushrooms back into the pan with the stock. Simmer for 15-20 mins until thickened, then stir in the Marmite. Give it a taste and adjust the seasoning with salt and pepper.

Heat the oven to 180°C. When your elements are ready to assemble, roll the pastry on a lightly floured surface, as big as the frying pan the filling is in. Brush the edges of the pan with a bit of the liquid from the filling then drape the pastry over the top, pressing the edges to the pan to seal. Cut a little cross in the middle to let the steam out and brush with a beaten egg. Transfer to the oven and cook for 25 mins, until golden and bubbling. Serve with mash and greens.