Preheat oven to 350F. Cut bacon into 1 inch pieces, fry, drain fat and reserve appropriate measure of drippings in the pan. Stir in onions, brown sugar, garlic salt, dry mustard, and ketchup. Simmer 20 minutes. Stir in beans and half of the measure of bacon. Spoon into casserole dish. Sprinkle with remaining bacon. Cover and bake for 50 minutes. Remove cover and bake 10 minutes longer. Serve hot.