In a large skillet, cook bacon; transfer it to a plate lined with a paper towel to drain. You may have to work in batches depending on your skillet size. Once it's cool, cut it into ½” pieces. If you prefer, you can cut the bacon into 1 inch pieces before you cook it.
½ pound bacon
Drain all but about 1 tablespoon of bacon grease from the pan.
Add chopped onions to the skillet and sauté them in bacon drippings until soft.
1 large onion, chopped
Add the ground beef to the skillet and cook until it’s no longer pink, breaking up chunks as it browns.
1 pound ground beef
While the meat is browning, whisk together brown sugar, ketchup, vinegar, dry mustard, and garlic powder in a medium bowl until smooth. Set aside.
1 cup light brown sugar, packed, 1 cup ketchup, 3 tablespoons white vinegar, 2 teaspoons dry mustard, 1 teaspoon garlic powder
Add the beans and bacon pieces to skillet and stir to combine with the ground beef mixture. Add sauce to the skillet and stir to combine. If your skillet isn't large enough, you can combine everything in the baking dish.
1 can (15.5 ounce) butter beans, rinsed and drained, 1 can (15.5 ounce) kidney beans, rinsed and drained, 1 can (15.25 ounce) lima beans, rinsed and drained, 1 can (16 ounce) pork and beans, undrained
Pour the mixture into a 9 x 13 inch baking dish or a large casserole dish. Cover with foil and bake for 45 minutes or until hot and bubbly.
Notes
Storage: Refrigerate leftover calico beans in an airtight container for up to 4 days. Freeze calico beans (cool completely first) in an airtight container for up to 3 months. Thaw in the refrigerator overnight. You can also put individual servings into freezer containers. Reheat in the microwave for 1 minute intervals, stirring in between, until heated through.
Make ahead: Calico beans may be frozen before baking for up to 3 months. Thaw overnight in refrigerator. Bake as directed.
Crockpot instructions: Prepare as instructed. Instead of baking the beans, put them into a slow cooker. Cover and cook on High for 3 to 4 hours, or on Low for 6 to 7 hours.
Possible substitutions: If you prefer, other types of beans can be substituted for the ones listed. You can also use ground turkey instead of beef. Omit the ground beef and bacon if you prefer vegetarian calico beans (add a teaspoon of smoked paprika or liquid smoke, if you like).