Preheat a Dutch oven over medium-high heat. Add a couple tablespoons of EVOO, 2 turns of the pan. Season chicken liberally with salt and pepper, and add to the hot oil, skin side down. Brown chicken, about 5 minutes per side. Remove and reserve.
Add another 2 turns of the pan of EVOO, the onions, thyme, honey and the garlic. Season the onions with salt and pepper, and cook, stirring frequently for about 20-30 minutes or until the onions are really brown.
Add cider vinegar, scraping up all the brown bits on the bottom of the pan with a wooden spoon. Add the chicken stock and bring up to a bubble.
Once at a simmer, return the chicken to the pot with the liquid and onions. Place a lid on the pot, turn the heat down to medium and simmer for about 15 minutes, flipping the chicken over in the sauce about halfway through. Remove lid, check to make sure the chicken is cooked through by cutting a small slit in the thickest part of the breast with a paring knife to have a look inside. If it is cooked through -- no pink meat -- remove to a plate and cover with foil to keep warm. Turn the heat up to high and simmer until the sauce thickens up slightly, about 4-5 minutes.
You can serve the chicken right away topped with a big spoon full of sauce and the onions or you can return the chicken to the pot, turn the heat off and cover with the lid until you're ready to serve it. Once you are ready, add 1/2-3/4 cup additional chicken stock and turn the heat back on to heat everything back up. Serve chicken with creamy Dijon smashed potatoes and a watercress and endive salad.