Basically, any bread you have around. Make sure it is sold by the loaf. You need to slice and cube the bread to your baking pan needs. I prefer a French baguette or crusty artisanal bread, but white, wheat, sourdough, brioche, or challah work as well. Make sure the bread is 1-2 days old for better results. Rye or any other strong-flavored bread would be too much for this simple dessert. The bread should be sturdy because it requires soaking in a combination of eggs and milk. If the bread is too thin or mushy during the cooking process, it will fall apart.