Preheat the oven to 350 degrees and line a 9″ square pan with parchment paper AND spray with baking spray.
Prepare the brownie mix according to the package directions and pour into the pan.
Press the 16 Oreos into the brownie mix, 4 x 4.
Bake for 27 minutes or until a toothpick comes out mostly clean.
Break the chocolate bars so that they fit on top of the brownies, place them on top and return to the oven for 2-3 more minutes until the chocolate is melted.
Spread the chocolate lightly with a spoon into an even layer. Add the patriotic sprinkles. Let it cool on a wire rack for about an hour and then transfer them to the fridge so the chocolate sets and the brownies get fudgy.
Before serving, let the brownies get to room temperature. If not the chocolate layer will be pretty hard to bite through!