Well, it wouldn't be right to leave the muesli bars half dressed (Excellent Museli Bars). So here is how to give them a nice chocolate topping. It doesn't get much simpler.
Step 1: Melt Chocolate...
The usual way, in a water bath.
Step 2: Spoon Into the Mould...
... and press in the previously finished muesli bars. Refrigerate to help set and 20 mins later, demold.
Depending on your skill with a Dremel or a laminate trimmer, you could personalise these with your kids names, your favourite quote from MLK, or parts of the legal code. Up to you.
I use only70% or more dark chocolate, but I imagine any cooking chocolate or hard setting topping would work. I also think you could try doing it in one step - pouring in the melted chocolate, and then spatula-ing the muesli mix and working it down. Not sure how clear the writing would come out, but why not try.