Heat a large pan over medium high heat. When hot, add the bacon and cook until the fat is rendered and the bacon is crisped. Remove the cooked bacon to a paper towel lined plate, leaving the grease in the pan.
Season the chicken with salt and pepper, to taste. Add the chicken breasts and cook for 3-5 minutes per side, or until cooked through. Remove to a serving plate.
Add onions and cook until soft, about 5 minutes. Add the garlic and cook until fragrant, about one minute more. Add the chicken broth, thyme, and bay leaf. Bring to a simmer and reduce the volume by half. Taste and adjust with salt and pepper. Stir in parsley and then pour sauce over the chicken. Sprinkle with bacon and serve.