Apparently, the Spanish-speaking world was fond enough of Pope Pius IX that it named desserts after him. Some describe them as looking like his head, but I guess it’s more his tiara or miter.
Here’s a Spanish site. The piononos of Santa Fe, which they claim are the original ones, look like a sort of popover-shaped cake or muffin. They describe them as “Spanish petit-fours”. They also have a blog, to attempt to make you drool.
Here’s some Malaga piononos.
Piononos in Argentina are a sort of elaborate jelly roll. Here’s a Peruvian egg company’s recipe for a similar four-egg pionono roll. Scroll down for one with 9 eggs, but most of that’s for the blancmange filling, I think. I guess that’s why other people make low calorie piononos. Another roll recipe.
This pionono recipe isn’t even a cake. It’s plantains stuffed with cheese and then corked with flour, eggs, and water. Puerto Rican roadside food booths apparently go with plantains and seasoned ground beef and then deep fry the puppy.
An Argentine-style bakery in Miami, FL, offers a salad version of a pionono! Italians apparently also feel that a pionono can be a salad or a sweet. In Uruguay, a pionono is a rolled submarine sandwich!
So if it’s cylindrical and yummy, it’s a pionono.