What I would do, is boil milk and get your cannabis simmering in there (to extract the THC), prepare you chocolate, drain your milk of the vegetable matter, mix yo' chocolate and milk, let it cool, drink.
I couldn't see any reason why it wouldn't work, it's the same as making cannabis hot chocolate which works very well.
If you use the search you could find the Hot Chocolate thread, as I say it's pretty much exactly the same and it does work (tried and tested).