Preheat the oven to 180C/350F. Line an 8 x 8-inch square pan with parchment paper, reserving 1-2 inches of parchment paper over the sides, for easily removal.
In a large mixing bowl, add all your ingredients, except for the chocolate chips, and mix well. Using a rubber spatula, fold through the chocolate chips, reserving a few to top the cookie bars with.
Transfer the batter into the lined pan, adding extra chocolate chips on top. Bake for 15-17 minutes, or until just beginning to go golden around the pan.
Remove from the oven and let sit for 10 minutes, before transferring to a wire rack to cool completely.
Notes
TO STORE: Leftover cookie bars should be stored in the refrigerator in a sealable container. They will keep fresh for up to 5 days. TO FREEZE: Wrap individual bars in parchment paper and place them in ziplock bags. They will freeze well for up to 6 months.