Heat oven to 350 degrees. Spray a 9x13 baking dish with non-stick cooking spray.
Add everything but the chocolate chips to a large mixing bowl and beat with an electric mixer until well combined.
Stir in the chocolate chips.
Spread the batter into the baking dish. Bake for 25 minutes or until a tester comes out with just a few moist crumbs. Bars should look slightly underdone.
Let cool 1 hour before cutting into bars.
Notes
You may swap the chocolate chips for raisins + a sprinkle of ground cinnamon, if you'd like oatmeal raisin bars.Be sure not to overbake the cookies. They'll look a bit underdone when you take them out, but they'll set up nicely as they cool.We prefer old fashioned or rolled oats in this recipe for the best texture.