Preheat oven to 325℉. Gather your ingredients so that you have everything close at hand on the counter or table.
Chop 1 cup sweet onion into small pieces.
Prepare the Beans
In a medium bowl, add 31 oz pork-n-beans, 3/4 cup brown sugar, 1/2 cup ketchup, 2 teaspoons yellow mustard, and diced onions. Season with 1/2 teaspoon kosher salt and 1/2 teaspoon freshly ground black pepper. Mix to combine.
Pour beans into a greased baking dish.
Add the Bacon
If desired, cook 4-6 slices thick sliced bacon in a large skillet until lightly browned. You may either chop the bacon into bite-size pieces or leave in strips. Top the beans with the bacon.
Bake uncovered in preheated oven for 2 -2 1/2 hours until the sauce is thick and bubbly. Allow to cool for 10-12 minutes before serving. Serves 6-8.