ID as per Page 218 in Caribbean Sea Slugs and as per Anne Diver via Nudibranch Hunters of Florida Facebook group. She is the photographer of this photo: http://www.jaxshells.org/doto.htm

It appears in Linda Ianiello's gallery as well: http://lindaiphotography.com/local-sea-slugs/

NOTE: "Varadero" means "drydock" in Spanish - and it is also the name of a large resort town in Cuba. https://en.wikipedia.org/wiki/Varadero Since I found this doto on a dock, the name seems extra appropriate.