Tim Maddam's gamekeeper’s pie

Ingredients

• 2 onions, peeled
• 1 carrot, peeled
• 1 celery stick
• A little rapeseed oil
• 500g minced game (whatever you have, see above)
• 100g minced pork belly (as fatty as possible)
• 3 garlic cloves, peeled and finely chopped
• A glass of red wine
• 400g tin good-quality peeled plum tomatoes, pushed through a sieve
• A sprig each of thyme and rosemary, finely chopped
• 1 litre game stock (see p.207), or any other meat stock
• A good pinch of ground mace
• 1 star anise
• Sea salt
• freshly ground black pepper
• 450g peeled celeriac
• 600ml whole milk
• 750g floury potatoes, such as King Edwards, peeled
• 100g butter, melted
• 1 egg yolk