Preheat oven to 360 degrees F.
Combine beans, onions, brown sugar, mustard, ketchup, salt, and pepper in a large baking dish. Lay bacon strips across top of beans. Squirt ketchup in a zig-zag pattern across the top of beans and bacon. Bake, uncovered, for 1 hour and 45 minutes.
Recipe courtesy of Mary Ann Casse