Healthier shepherd's pie recipe

Ingredients

• 1 tbsp rapeseed oil
• 1 onion, finely chopped
• 3 carrots, chopped into 1cm dice
• 150g button mushrooms, quartered or cut into chunks if large
• 2 garlic cloves, crushed
• 150g 10% lean lamb mince
• 250g ready-cooked puy lentils (we used Merchant Gourmet)
• 2 tbsp tomato purée
• 400g tin chopped tomatoes
• 200ml beef or lamb stock
• Handful fresh oregano, chopped
• 3 tbsp Worcestershire sauce
• 350g maris piper potatoes, cut into chunks
• 350g cauliflower, cut into florets
• 10g butter
• 20g parmesan, finely grated