Preheat oven to 350°F. Line a 9x13-inch baking sheet with parchment paper or aluminum foil, allowing the edges to overhang slightly. Spray lightly with cooking spray. Set aside.
Place the cake mix, oil, and eggs in a large bowl and mix with a wooden spoon or rubber spatula until well combined. With clean hands, press the dough evenly into the prepared pan.
Bake the dough for 10 minutes.
Remove the pan from the oven and immediately top with OREO cookies, cookies 'n' creme bars, and the chocolate chip cookie dough bites. Drizzle the sweetened condensed milk over the top, evenly covering the bars.
Return the pan to the oven and bake for an additional 12-15 minutes.
Allow the bars to cool on a wired rack completely before removing the bars from the pan to serve. Cut into squares.
