This hearty baked bean casserole is loaded with four types of beans, crispy bacon, and tender onions. A sweet and tangy sauce made from brown sugar, apple cider vinegar, and savory bacon drippings brings the whole dish together. It is a perfect side for a summer barbecue, a neighborhood potluck, or a comforting weeknight dinner. The slow bake creates a rich, smoky flavor with a satisfying balance of sweet and sharp notes.
1Heat your oven to 350°F. Place a large skillet over medium-high heat and cook the bacon in batches until it is fully crisp, which takes about 8 to 10 minutes.
2Transfer the cooked bacon to a paper towel-lined plate to drain. Keep about 3 tablespoons of the bacon drippings in the skillet and discard the rest. Crumble the cooled bacon into bite-sized pieces.
3Lower the heat to medium and cook the sliced onions in the reserved bacon drippings for 8 to 10 minutes until they are soft. Stir in the brown sugar, apple cider vinegar, kosher salt, dry mustard, and garlic powder. Place a lid on the skillet and let the mixture cook for 20 minutes.
4Transfer the cooked onion mixture into a 13- by 9-inch baking dish. Add the drained butter beans, lima beans, kidney beans, and the entire can of baked beans, then stir everything together until well combined.
5Place the baking dish in the preheated oven and bake uncovered for 1 hour until the sauce is bubbly and thick.