• Trim the chicken thighs of excess fat. Place the chicken thighs and legs in a large bowl and pour in the whole bottle of burgundy. Marinate the chicken for at least 2 hours, but if possible overnight.
• Preheat oven to 350f and set the rack in the middle level, allowing enough room to accommodate a large Dutch oven with a lid.
• Heat a large Dutch oven to medium heat and add the bacon. Cook the bacon until most of the fat has rendered (7-10 minutes) then remove the bacon with a slotted spoon to a paper towel-lined plate to drain.
• Meanwhile, remove the chicken from the bowl and place onto a work surface, making sure to save all of the wine. Pat both the legs and thighs very dry and season with salt and pepper on all sides. Dredge the chicken pieces in flour and shake off all of the excess. Sear the chicken pieces in the bacon and chicken fat until well browned on all sides, working in batches if necessary. Place all of the chicken onto another plate and set aside.
• Remove excess bacon and chicken fat from the pot, leaving approximately a quarter cup in the pot. Add the onions, carrot, and celery to the pot and cook for 10-12 minutes or until they begin to soften then add the garlic and cook for another 2 minutes or until very fragrant.
• Add the tomato paste and cook for another 3-4 minutes, stirring frequently to avoid burning. If it starts to burn just add a couple of ounces of water into the pot to lower the temperature.
• Add the wine and chicken stock to the pot and bring to a boil for 2 minutes. Using a flat wooden spoon, scrape the bottom of the pot to remove all of the brown bits.
• Turn off the heat and add the chicken, bacon, thyme, and bay leaves to the pot. Cover the pot and place it in the oven to cook for 75-90 minutes or until the chicken is very tender.

For finishing

• Once the chicken is tender remove the chicken to a plate and cover with foil to keep warm. At this time, discard the bay leaves and thyme from the sauce.
• Skim any visible fat from the top of the sauce pot then place the pot onto a burner and turn the heat to medium-high. Reduce the sauce until thickened by about half (about 10 minutes). The sauce should be quite thick and will coat the back of a wooden spoon. Once reduced, taste test, and season with salt and pepper. Add the chocolate and mix until smooth. Place the chicken into the pot and mix well to coat. Cover with the lid and set aside.
• Heat a large pan to a touch higher than medium heat. Add the olive oil along with the pearl onions. Cook the onions until tender (about 3-5 minutes) then remove with a slotted spoon into a plate that is covered with foil.
• Add the mushrooms to the same pan and cook until they release their water and start to brown (about 5-8 minutes). Once they begin to brown add the butter and cook until they are glistening (about 2-3 minutes). Return the pearl onions back to the pan and toss/mix to coat. Turn off the heat and season with salt and pepper and the thyme leaves.
• Mix the parsley into the pot. You can mix all the mushrooms and pearl onions into the pot right before serving or divide them onto plates so that each person gets a few pearl onions and mushrooms. Serve with mashed potatoes or crusty bread. See notes below about serving the next day which is preferred.