Preheat oven to 350 degrees. Spray a 2 to 3-quart casserole dish with cooking spray. Set aside.
Place the bacon in a skillet or saute pan and cook for 4-5 minutes over medium heat until rendered and crispy. Transfer to a paper towel-lined plate.
Place the onion in the skillet with the bacon drippings and cook for 5-6 minutes or until very soft. If the pan gets dry, add 1-2 tablespoons of water and continue cooking until the onions are cooked to a soft stage.
Combine the beans, onions, ¾ of the bacon and the remaining ingredients using 2 tablespoons of brown sugar to start with in the prepared baking dish.
Taste and adjust sweetness with more brown sugar as desired. Add the apple cider vinegar for a little tanginess if you desire.
Sprinkle the remaining bacon over the top.
Bake uncovered for 1 hour or until bubbling and the top is caramelized.
