How do I make a brownie chip?
I think what you would want to do is reduce the amount of fat in the recipe, as there is no way to get fat to dry out (well, except by using n-zorbit). Maybe use more cocoa powder and less chocolate, and skip or reduce any butter or other fats. Add more water or skim milk as needed to get a spreadable batter. Then proceed as you are currently doing, baking it as thin as possible. I would aim for a longer time at a lower temperature as that will produce more even baking, instead of only crisp at the edges.