Preheat the oven to 325 degrees (F). Line a 9x13-inch baking pan with parchment paper - letting the excess hang over the edges of the pan by about 1 inch so that removing the baked bars is easy once baked. Spray the parchment paper and any exposed pan with nonstick cooking spray. Set aside.

Whisk the melted oil and sugars in a large bowl until combined. You can do this by hand, but I recommend using a handheld mixer if you own one, as it the by hand method takes a lot of elbow grease. Once the oil and sugar are well combined, add the cinnamon and eggs and mix well.

Add in the flours and salt, and using a rubber spatula, fold the dry ingredients into the egg mixture until just combined; do not overmix.

Fold in the chocolate chunks and then pour the batter into the prepared pan, smoothing the top with the spatula. *The batter will be very thick; this is normal ;) You can use a piece of plastic wrap to press it into the pan if you don't have a strong enough spatula.

Place the pan in the oven and bake until the top of the bars is golden brown, and just slightly firm to the touch; about 25-28 minutes.

Cool on a wire rack until they reach room temperature.

Remove the bars from the pan by lifting the parchment paper overhang and transfer them to a cutting board. Cut into small squares and serve.

*Bars will stay fresh for up to 3 days when stored in an airtight container.