On my 600k brevet, I loved soup. Unlike Road Raven, I wouldn't go for creamy, though, but that's sort of a personal thing, I guess. (Tends to make my nose stuffy and I also feel it might be too rich.) I do agree a hearty, salty soup is great and usually goes down well. Lentil or minestrone come to mind.

Simple food like sandwiches also goes well on a long ride. I will usually have this on a double century. Just simple bread, meat, cheese with some mustard.

Hydration and electrolyte replacement is almost more important than food if it is hot out. Be sure to have sports drinks or something to replace electrolytes. I don't suppose Endurolytes are readily available in Croatia, but there should be something similar. Even a chewable antacid can sometimes have the right ingredients.

Have fun!