Shepherd's Pie with Minted Peas - Ainsley Harriott

Ingredients

• 2 tbsp olive oil
• 1 large onion, finely chopped
• 225g peeled carrots, finely diced
• 1-2 sticks of celery, trimmed, finely diced
• 900g minced lamb
• 3 sprigs of thyme, leaves picked
• 1 tbsp Worcestershire sauce
• 1 tsp tomato purée
• squeeze of tomato ketchup
• 1 bay leaf
• 300-350ml lamb, chicken or vegetable stock
• salt and freshly ground black pepper
• For the Mash
• 1.5 kg peeled floury potatoes, such as Maris Piper, cut into chunks
• 50g butter, melted, plus extra for brushing
• 60-70ml milk
• fresh nutmeg, for grating
• ground white pepper
• For the Minted Peas
• 300g frozen petit pois
• 1-2 tbsp butter
• 1 tbsp finely chopped fresh mint
• zest of ½ lemon
• To Serve
• 1 tbsp chopped fresh parsley