How to Make chocolate bars with surprise fillings

You know how people always get frustrated when they open up a Valentine's Day chocolate gift box to find no labeling device for the chocolates there, forcing them to taste test each one to see if they like 'em? Recreate this frustration and relish in the schadenfreude by baking these melt in your mouth chocolate bars, each one filled with something different, from caramel and peanuts to almonds and more chocolate.

Of course, given that all of the fillings for these chocolate bars are universally delicious (come on, who doesn't like caramel?), your taste testers will probably end up more satisfied than frustrated.