Add the onions to the drippings in the pan. Cook for about five minutes, stirring frequently until the onions become a soft golden brown. Add the mushrooms. Saute for approximately three more minutes over medium high heat until the mushrooms are browned and slightly caramelized.
Add the fresh thyme leaves and balsamic to the mushrooms and onions, de-glazing the pan by scraping up any browned bits from the bottom. Cook to reduce for a minute. Add the cream and stir to combine. Add the bacon and reserved chicken. Allow the pan to come to a simmer. Cook for another two minutes until the chicken is cooked through and the sauce thickens. Season generously with sea salt and fresh ground pepper. Serve over pasta, rice, or cooked whole grains.