13. Bitterballen, Netherlands

So many of the world's comfort foods evolved as a way to use up leftovers. Made with scraps of meat from the weekend roast, bitterballen – Dutch meatballs – are no different. Here, a crispy, crumbed exterior envelops small pieces of beef in a béchamel sauce. Though they're rarely made in Dutch homes these days, they remain a popular bar snack and can be bought from takeout spots with a side of fries. Soft, gooey perfection!