preheat oven to 350° and prepare pan by spritzing with cooking spray. I even lightly spritz my silicone pan.
In a small bowl, mix together applesauce, vanilla, and apple cidar vinegar. Set aside.
In a larger bowl, mix together flour, sugar, cocoa, baking poweder, cornstarch, baking soda, salt, and cinnamon. Set aside.
Chop walnuts if using and measure out chocolate chips.
Add applesauce mixture, walnuts and chocolate chips to dry ingredients all at once and stir well to moisten dry ingredients. Do not over-mix.
Pour into a prepared pan and bake for 25 - 30 minutes. You will know if your brownies are finished because the top will be slightly firm when pressing. The toothpick method might also work if you can find an area without chocolate chips on top or in the brownie.