Shred any leftover meat from the chicken and set aside. Put the chicken carcass, onion skins and peppercorns into a deep saucepan. You can also add the trimmed ends of the onions, carrots, parsnip and celery. Season with a pinch of salt and pour over enough cold water to cover the chicken carcass, around 1.5 litres. Bring to a simmer on a medium heat, then gently simmer for 45 mins-1 hr, skimming away any scum that rises to the surface. Using a potato masher, break up the chicken carcass to extract more flavour. Pour the stock through a fine sieve into a large bowl, pressing down on the bones again. Discard the contents of the sieve and set the stock aside. You should have around 1 litre.

Spoon any leftover fat and juices from the roasted chicken tray into a flameproof casserole dish and melt over a medium heat. Tip in the onions, carrots, parsnip, celery and garlic, and fry, partially covered, over a low heat for 8-10 mins until softened. Mix in the plain flour, bay leaves and half the thyme, cook for a couple of minutes, then add the stock and shredded chicken. Bring back to a gentle simmer and cook for 15-20 mins until everything is tender. Season.

Tip the self-raising flour, butter and remaining thyme into a bowl with 1/2 tsp fine sea salt. Rub the butter into the flour using your fingertips until it resembles fine breadcrumbs. Pour in 60ml of the milk and stir together using a cutlery knife until it clumps together into a soft dough. Add a splash more milk if needed. Bring the dough together using your hands and divide into 12 balls. Dot the balls on top of the stew and cover with the lid. Turn the heat back up to medium and cook for 25-30 mins until risen, fluffy and cooked through.