Preheat the oven to 350°F. Grease an 8x8-inch baking pan with nonstick cooking spray.

Melt the butter and transfer it to a large mixing bowl. Add the eggs and beat until completely combined.

Add the dry yellow cake mix and mix until a thick cookie dough forms.

Fold in the semi-sweet chocolate chips until they are evenly distributed throughout the dough.

Transfer the dough to the prepared pan and press it into an even layer.

Bake on the center rack for 20 to 25 minutes, or until the top is lightly golden and the center appears set.

Allow the cookie bars to cool completely in the pan before slicing.

Cut into squares and serve on their own or with milk or vanilla ice cream.