Heat a large skillet over medium-high heat and add bacon pieces. Cook for 5 to 7 minutes until crispy.

Use a slotted spoon to transfer cooked bacon to a paper towel-lined plate, leaving bacon fat in the skillet.

Add diced onion to the skillet and cook for 4 to 5 minutes until soft and beginning to caramelize.

While onion cooks, open all four cans of beans, drain, and rinse under cold water.

In a small bowl, whisk together brown sugar, apple cider vinegar, ketchup, mustard powder, garlic powder, black pepper, and salt until smooth.

Add drained beans to the skillet with onion. Pour sauce mixture over beans and stir to coat evenly.

Pour the bean mixture into a 9x13 inch baking dish and scatter cooked bacon pieces on top.

Preheat oven to 350 degrees Fahrenheit and bake uncovered for 45 minutes until bubbly and edges brown.

Remove from oven and let rest for 5 minutes before serving.