Preheat the oven to 350°F. Spray a 9 x 13 baking pan with nonstick cooking spray, or butter it.
Mix the brownie mix according to package directions, following the brownie recipe, but incorporating all of the chips into the batter. In another bowl, mix the cookie mix with the Butterfinger baking bits according to package directions, following the cookies instructions.
Spread the brownie mix into the prepared pan in an even layer (see Note). Using your fingers take pieces of the cookie mix and flatten it into about 1/4-inch disks, and then assemble those on top of the brownie layer, using your hands to patch the pieces together to form the second layer without disturbing the bottom brownie layer to much. It sounds complicated, but you’re just making a cookie dough puzzle and then assembling it on top of brownies. That’s a nice thought, right?
Bake for 25 to 30 minutes, until the edges are lightly browned and starting to pull away from the sides of the pan. A toothpick inserted in the middle of the pan should come out mostly clean, though if you hit a melted chocolate chip you will see some melted chocolate. If that happens, poke the brownies in another spot or two to determine if the brownies are done.
Cool the brownies completely in the pan on a wire rack. Cut into 15 to 24 squares, as desired.
Notes
Answer:
24, if you want to consider in which order you can layer the combo options a different combo, 16 if you want to know just how many combos there are irrespective of which flavor is on the top or on the bottom. Here is how I got there..
Note:
I made these a few different ways, and while I kind of like the look of the "blondie" layer on tap, in fact that thicker batter layer is easier to spread on the bottom of the pan, while the looser brownie mix spreads more easily top top. Both are highly doable, and exploring which you like best is a pleasurable exercise.