Mix meat, egg, crumbs, cheese and salt.Cut top and bottom off onion, cut in half and peel off skin. Then separate the onion into layers. Use the larger outside layers.Take a small handful of your meatloaf mix and put it inside one onion layer.Gently press another layer on top of the mixture. You are making an onion seal around your large meatball.Continue with the rest. I made 4 but amounts can vary based on onion sizes.Wrap each "bomb" with 3 slices bacon and secure with toothpicks.Bake in a dish with sides (to catch grease) at 425 for approx 40 minutes or until internal temp 165.Add BBQ sauce all over and bake an additional 5 minutes!