Spray 12 jelly jars with non-stick cooking spray & place them on a rimmed baking sheet.
Prepare the brownie mix as directed on the package.
Divide it evenly between the jelly jars, filling the jars approximately halfway full.
Bake for 25 minutes and check for doneness by inserting a toothpick and if it comes out clean, they should be done.
Allow to fully cool on a cooling rack.
When the brownies have cooled, combine the unwrapped caramels and the whipping cream in a heavy, small saucepan over low heat. Stir constantly until the caramels have melted.
Working quickly, spoon evenly between all of the jelly jars to cover the top of the brownie and immediately sprinkle with the pecans, pushing them into the caramel if needed to secure them.
As the caramel begins to solidify, sprinkle with the chocolate chunks and push them into the caramel to secure them as needed.