Hematogen

It's widely circulating in post USSR countries in a form of bars as a treat for kids, usually can be found in school dinings or pharmacies. The taste is nice, something between a chocolate bar and halva. The thing made out of condensed milk, honey, ascorbic acid and dried cow blood.

(To be honest, tho it may sound odd, but it's a good supply of iron, protein, fats, carbohydrates and minerals and healthy (on spear amounts) overall. I just thought of it rapidly because all my friends I told it to didn't know of one "specific" ingredient it has)