• Preheat the oven to 220°C/200°C fan/gas mark 7.
• Boil a large pot of salted water for the potatoes. 
• Chop the potatoes into 2cm chunks (peeling optional). 
• Add the potatoes to the boiling water and cook until fork tender, 12-18 mins. Once cooked, drain in a colander and return to the pot, off the heat. 
• Add a knob of butter and a splash of milk or water. Mash until smooth. Season with salt and pepper.

• Meanwhile, halve, peel and thinly slice the onion.
• Peel and grate the garlic.
• Roughly chop the mushrooms.
• Pick the thyme leaves and roughly chop (discard the stalks).

• Place a large pan over medium heat with a drizzle of oil.
• When hot, add the onion and cook until softened, 2-3 mins. 
• Add the mushrooms, thyme and garlic and cook, stirring, until mushrooms are starting to char, 3-4 mins.
• Season with salt and pepper.

• Add peas, Worcester sauce and passata to the pan.
• Cook, stirring often, until the veg is coated, 1-2 mins. 
• Add stock powder, ½ tsp sugar and 50ml water (double both for 4p). Bring to the boil.
• Once boiling, reduce heat to medium-low.
• Cook, stirring often, until sauce thickens slightly and veg is tender, 3-4 mins. Add a knob of butter and season to taste with salt, pepper and sugar.

TIP: Add a splash of water if you feel the sauce is too thick.

• Transfer the filling to an appropriately-sized oven dish.
• Top with the mashed potatoes. Use a spoon to spread out in an even layer.
• Sprinkle the cheese over the top.
• Bake on the middle shelf of the oven until the topping begins to brown, 5-6 mins.

• Remove your mushroom cottage pie from the oven.
• Allow to cool before serving, 1-2 mins. 
• Divide between plates.