Bolo do caco is a traditional bread from the island of Madeira in Portugal. This simple yet distinctive bread is made with flour, yeast, salt, water, and sweet potatoes. Sweet potatoes were introduced to Madeira around the 16th century, and the island’s mild climate, ample sun, and advanced irrigation techniques support an abundant sweet potato harvest. Wheat, however, doesn’t grow as well on Madeira’s hilly terrain.By adding sweet potatoes to the bread, locals could stretch limited wheat supplies. The word bolo means "cake" in Portuguese, while caco refers to the flat stone slab used to cook the bread, traditionally heated over open embers.Because basalt stones were widely available, they became the preferred surface for cooking bolo do caco. Ovens, being expensive to build, were typically beyond the reach of poorer residents, making this method accessible to most people.