Prepare the Batter

1. Preheat Oven: Start by preheating your oven to 350°F (175°C) and greasing a 9×9-inch or 9×13-inch baking pan. If you prefer, you can line the pan with parchment paper for easy removal later.
2. Mix the Ingredients: In a large bowl, combine the cake mix, vegetable oil, and eggs. Stir until well combined—this part should only take about a minute or two. If you’re adding any mix-ins, fold them in now.
3. Pour into Pan: Pour the batter into the prepared pan and spread it out evenly with a spatula.

Bake the Cookie Bars

1. Bake: Place the pan in the preheated oven and bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean or with just a few moist crumbs. The edges should be lightly golden.
2. Cool: Allow the cookie bars to cool in the pan for about 10 minutes before transferring them to a wire rack to cool completely. If you’re in a hurry, you can let them cool in the pan.

Slice and Serve

1. Slice the Bars: Once cooled, slice the cookie bars into squares or rectangles, depending on your preference. You can cut them into bigger or smaller pieces, depending on how you want to serve them.
2. Enjoy: Grab a plate, and enjoy your freshly baked cookie bars! They’re soft, chewy, and oh-so-satisfying.