Dice the mushrooms and celery, and finely mince the garlic.
Remove the fat from the bacon, and dice finely.
Heat some butter, oil or cooking spray in a large frying pan or pot. Add the mushrooms, and fry until they have reduced in size and slightly softened. Remove them from the pan and set them to the side.
Add the garlic and bacon to the pan and fry until the bacon has mostly cooked through, about 2-3 minutes.
Add the chicken thighs with the skin side up, and cook until they start browning in color, about 5-7 minutes. Then turn them skin side down, and cook until they brown on the other side, about 5-7 minutes. You might have to cook the chicken in batches if your pan isn't big enough to fit all the chicken pieces without them being crammed together.
Turn them again with skin side up, and add the stock, red wine, silverskin onions, bay leaves, thyme, rosemary and mushrooms. Leave to simmer for 45 minutes, preferably under a lid.
Add the diced celery, and leave to simmer until the chicken has cooked through and is tender, about 30 minutes. Use a meat thermometer to ensure that the chicken has reached an inner temperature of 75°C or 165°F before finishing the dish.
Add 2 tablespoon cornflour to a small bowl, and add a few tablespoon of the red wine sauce. Stir to combine until there's no lumps, then add the mixture to the pan. Distribute the cornflour through the sauce. Leave it to cook for another 5 minutes, and the sauce will have thickened.