1. Preheat oven to 350℉ and grease a 8” square pan.
2. In a medium sized bowl, combine cake mix, oil, water, vanilla and (optional) sugar.
3. Whisk until well incorporated, about 1 minute.
4. Fold in the chocolate chips.
5. Pour the batter into prepared pan and bake for 30-40 minutes, or until a toothpick inserted comes out clean.
6. Let cool for 15 minutes, cut into squares and serve!