Have you heard of 'raw chocolate'? it is a superfood and I have started giving it to my kids occasionally to boost them up. you can either buy it ready made or make it up yourself.
if you want to buy it ready-made then try this site:
http://www.therawchocolateshop.com/
If you are happy to make it yourself - you can then put it into fun moulds which kids like and it's cheaper this way - then try out Well Necessities - their site address is:
http://www.wellnecessities.co.uk
If you aren't sure if your kids will like it then you can save money by buying a 'starter kit' to try out - http://www.wellnecessities.co.uk/starterkit.html
I bought the £6 make your own chocolate starter kit. It was very easy to make and the kids can do it because you don't use boiling water. They liked pouring them into different moulds.
If your kids have a sweet tooth like my two do then you can sweeten it more by adding some honey. you can also throw in some other 'superfoods' like cranberries, finally chopped almonds etc. It's quite expensive so I give my boys just one small chocolate a day and it's great knowing it's actually good for them.
worth a try if you have very fussy eaters like i do!
Kitty