Well, a mollete (*) isn´t exactly a muffin either.
A mollete is a round and flat bread roll we usually have for breakfast. Its main traits are a very soft crust and a very spongy crumb.
It doesn´t matter if its white bread or wholemeal, both types are available.
I don´t know which English word would suit better for that, in case there´s one.
This type of bread is typical from Andalusia -Southern Spain- so, being such a local product, I´m not sure if it deserves much investigation beyond finding an approximate equivalent in English.
(*) It can also mean flab in Spain at least, but in a very colloquial way. I wouldn´t say this meaning is widely used either.
I agree with you two. Sometimes, if the context requires the original word, I think we can leave it in Spanish, just like we do with words like croissant or doughnut, words that nobody translates into Spanish or other languages.