Preheat oven to 350 degrees. Grease a 9x13 inch baking pan and line it with parchment paper.
In a large mixing bowl, combine all the crust ingredients - cake mix, egg and butter until you get a thick batter.
Use a whisk to mix all the ingredients evenly.
Spread the mixture into the prepared pan and press evenly into the bottom.
In the same bowl, combine the cream cheese, eggs, vanilla and sugar and mix well using an electric mixer. Pour the mixture on top of the cookie mixture.
Bake at 350 degrees for about 30-35 minutes.
Allow to cool down before cutting into squares.
Notes
Remember to use room temperature cream cheese as the topping for these cookie bars. Make sure you don’t end up overcooking the bars. You still want them to have a slightly chewy texture. A 9x13 baking sheet or tray is perfect for a single box of cake mix. This will make sure the bars have the perfect thickness. If you use a smaller pan, the bars will be thicker. If you have any leftovers that you want to store for later, you can refrigerate them in an airtight container for up to 5 days. Before you serve them, get them out and let them get to room temperature and soften before you enjoy them.