How to Make My Grandma's Quorn Shepherd's Pie

Ingredients

• 1 tablespoon olive oil
• 150 g chestnut mushrooms, chopped
• 2 medium carrots, halved lengthways and sliced thickly
• 1 small leek, sliced fairly finely
• 150 g Quorn mince
• 1 vegetable stock cube
• 400 g tin chopped tomatoes
• 1 tablespoon tomato puree
• Salt and pepper, to taste
• 1 kg baking potatoes, peeled and chopped into small chunks
• 20 g butter
• A splash of milk
• 100 g mature cheddar cheese, grated (75g for the mash, 25g for topping)
• Peas and/or sweetcorn, for serving