Preheat oven to 350 degrees F. Line an 8x8-inch square baking dish with parchment paper.
Combine all dry ingredients (except chocolate) in a large bowl.
Add softened butter, egg, and vanilla extract, and stir until combined.
Fold in chocolate chips or chunks.
Spread batter evenly into baking dish, and top with extra chocolate chunks or chips if desired. (note: batter may seem thin when spread into pan, but will rise while baking. If you prefer thicker bars, add extra chocolate chips or bake in a smaller pan.)
Bake for about 20-25 minutes, or until lightly golden brown on the edges. Check early and often as different ovens are different, and you don't want to over-bake these.
Allow to cool, slice, and enjoy!
Notes
*I use Lakanto - 20% off: SARAH**I use either Choc Zero sugar-free milk chocolate chips, Choc Zero chopped chocolate squares, or Lily's sugar-free chips or chopped bars. For Choc Zero you can use code SARAH for 10% off. For the purposes of calculating the nutritional info for this recipe, I used Choc Zero milk chocolate chips.