Preheat oven to 400°F. Grease a 2 ½ - 3-quart baking dish with nonstick cooking spray; set aside.
Cook the bacon in a large skillet over medium heat until crisp, about 7-10 minutes. Transfer the bacon to a paper towel-lined plate. Reserve about 1 tablespoon of bacon drippings in the skillet; discard the rest.
Using the same skillet, cook the ground beef, bell pepper, and onion in the reserved bacon drippings over medium-high heat until the meat is no longer pink. Add the garlic and cook for 1 more minute. Drain off excess grease. Stir in bbq sauce, baked beans, and cooked bacon. Cook over low heat, stirring occasionally, until hot and bubbly, about 3-5 minutes. Taste and season with salt and pepper, if desired. Transfer to the prepared baking dish. Sprinkle shredded cheese on top.
In a medium bowl, whisk together the buttermilk, oil, and egg. Add the self-rising cornmeal mix and sugar. Stir just until combined. Spread the cornbread batter over the top of the cheese and warm beef mixture.
Bake, uncovered, until the top is golden brown and cooked through, about 35-40 minutes.