Mash potatoes & add other wet ingredients. Stir well.
Add all dry ingredients except chocolate chips. Stir to combine. Add chips.
Pour batter into an 8x8 pan and bake at 350° for 20-25 minutes. Store in the fridge. Good for up to a week. If doubling recipe, bake in a 9 x 13 dish for 35-40 minutes.