Season the chicken thighs with salt and pepper. Melt half the butter in a deep frying pan or large flameproof casserole over a medium heat and cook the chicken, skin-side down, for 10 mins until deep golden. Flip to seal the fleshy side for a few minutes – you may need to do this in batches. Put in the slow cooker.

Tip the bacon into the same pan and fry for 5-6 mins until crisp, then add to the slow cooker. Tip the onions or shallots and carrots into the pan and fry in the bacon fat for 5 mins until starting to colour. Add the garlic, cook for 1 min more, then sprinkle over the flour and cook for 1-2 mins until you have a sandy paste. Stir through the tomato purée and cook for 2 mins more. Bring to the boil, then turn down to a simmer for 2 mins.

Tip the contents of the pan over the browned chicken. Pour the stock and wine into the pan, bring to the boil, then pour into the slow cooker. Nestle in the bay leaves and thyme, season, then set the slow cooker on high for 3-4 hrs, 5-6 hrs on medium or 7-8 hrs on low, stirring once or twice, until the chicken is tender.

While the chicken cooks, heat the remaining butter in a clean pan and fry the mushrooms for 4-5 mins over a medium heat. Tip into the slow cooker about an hour before the end of cooking and stir. At this stage, the coq au vin can be cooled and kept chilled for up to three days or frozen for up to three months. Defrost and reheat in a pan over a medium heat until piping hot. Scatter over the parsley, if using, and serve with mash or buttered tagliatelle.