Preheat oven to 325°F (163°C). Spray a 3-quart baking dish with nonstick cooking spray.
Cook the bacon (4 ounces), in a large skillet, until crisp. Remove to a paper towel-lined plate. Discard bacon grease (I freeze mine to use in other recipes, like THIS one.)
Using the same skillet, cook ground beef (1 pound) and onion (1 cup), over medium heat until the beef is done and there is no longer any pink. Drain off excess fat. Combine the cooked beef and bacon with beans, brown sugar (1/2 cup), ketchup (1/2 cup), water (1/4 cup), apple cider vinegar (1 tablespoon), dry mustard (1 teaspoon), salt (1 teaspoon), and liquid smoke (1/2 teaspoon). Spoon into the prepared baking dish.
Bake, uncovered, 45-60 minutes or until beans have desired thickness.
Notes
Baking: Baking in the oven helps to marry the flavors, of course, but it also helps thicken the sauce. I usually bake mine in close to an hour, but you can adjust that based on your own oven and preference for having extra sauce for dipping that cornbread in or a thicker, stick-to-your-ribs stew-like quality.