Preheat oven or smoker to 325 degrees F.

Chop bacon and fry in a large pan or cast iron skillet over medium-high by stirring with a wooden spoon until crispy. Transfer to a plate lined with paper towels using a slotted spoon, then remove all but about ¼ cup of the bacon drippings.

Add the onion and green pepper to the pan with the bacon grease and sauté over medium heat until they have softened and begin to caramelize, around 5-7 minutes. Add garlic and continue to cook and stir for another 30 seconds.

Add beans, reserved bacon, ketchup, brown sugar, Worcestershire sauce, mustard, and black pepper and stir to combine. Bring to a simmer, then transfer the pan to the oven or smoker if using a large, oven safe cast iron skillet, or pour the beans into a large 9x13-inch pan first before placing in the oven or smoker.

Bake for 1-2 hours until the beans are hot and bubbly and have achieved the thickness you desire. Keep in mind that the beans will continue to thicken slightly as they cool.