Eat all the chocolate you want. As long as calories in is less than calories out you'll lose weight.
True, but I'm currently aiming for a leaner build so want to avoid extra calories that I don't need
If you are craving chocolate, you are probably craving magnesium. Unless you are really looking for an excuse to eat chocolate (not going to judge you), you can try to eat something else magnesium rich (or even a magnesium supplement) and that should do the trick.