Preheat oven to 350°F. Grease a 2 – 3 -quart baking dish; set aside.
Heat a large skillet or Dutch oven over medium-high heat. Add the beef, onion, and bell pepper; cook until the meat is no longer pink, about 5-7 minutes. Drain off excess grease. Stir in pork and beans, ketchup, brown sugar, mustard, Worcestershire sauce, vinegar, chili powder, salt, and pepper. Simmer the mixture for about 5 minutes.
Transfer the beef and beans to the prepared baking dish. Sprinkle bacon on top. Cover with foil and bake for 40 minutes. Remove cover; continue baking for 10 more minutes.
Let the dish rest for 10 minutes, then serve!
Alternate slow cooker method: Brown the beef and vegetables on the stovetop, as instructed. Simmer with the other ingredients for 5 minutes, and then transfer the mixture to a Crock Pot. Do not add the bacon yet. Cover and cook on HIGH for 1-2 hours or on LOW for 3-4 hours. Remove the cover during the final 30 minutes, sprinkle the bacon on top, and continue cooking without the lid to allow the sauce to thicken slightly.
This dish serves about 6-8 people as a side dish, or about 4 people as a main dish entree. If you're feeding a larger group, double all of the ingredients and bake the beans in a 9 x 13-inch casserole dish.
The total cooking time may vary. For really soft, broken-down beans or a thicker sauce, you might like to leave the dish in the oven a little bit longer.
The beans and sauce will continue to thicken as they cool, so don’t worry if it looks a little bit soupy when it first comes out of the oven.
For added heat, season the beans with Cajun seasoning or Creole seasoning, some hot sauce, or a dash of cayenne.