Program your oven to 375F, then place the diced bacon into a cast-iron skillet over medium-high heat. Sauté the bacon until it is crispy and golden brown, then remove it from the pan, place it on a paper towel lined-plate lined, and set it aside.
Add the onions to the skillet and sauté for 6-7 minutes until they have softened and are just beginning to caramelize. Stir in the garlic and green peppers and cook for 1minute until the garlic is fragrant.
Add the pinto beans, great northern beans, baked beans, red kidney beans, ketchup, maple syrup, hot sauce, brown sugar, Worcestershire sauce, mustard, apple cider vinegar, smoked paprika, black pepper, and cooked bacon.
Stir to combine and transfer the bbq beans to a 9x13 baking pan, cover it with aluminum foil, and bake, covered with foil, for one hour. Remove the foil and bake the bbq beans for another 10 minutes.
Serve and enjoy!