Cottage pie - James Martin Chef

Ingredients

• 8 medium baking potatoes
• 1 tablespoon vegetable oil, plus extra for rubbing
• rock salt
• 600g minced beef
• 2 onions, finely chopped
• 3 garlic cloves, finely chopped
• 4 sprigs of thyme, leaves picked and finely chopped
• 1 celery stick, finely diced
• 2 tablespoons tomato purée Worcestershire sauce, to taste
• 9 carrots, unpeeled
• 100ml red wine 500ml beef stock
• salt and freshly ground black pepper
• 50g caster sugar
• 125g unsalted butter
• 150ml milk