Preheat oven to 350°; line two baking sheets with parchment paper or use a silpat.
In a medium bowl, whisk together flour, baking powder, baking soda, salt and cinnamon.
In a large bowl, with a mixer, cream together the butter and the sugars on medium speed.
Add the egg, followed by the applesauce and vanilla extract.
Working by hand, stir in the flour mixture and the oats until just combined and no streaks of flour remain; stir in the chocolate chips.
Drop heaping tablespoonfuls (approx 1 tbsp each) of the dough onto prepared baking sheets, flattening each cookie slightly (I forgot to do this).
Bake for about 10-12 minutes, or until cookies become light brown at the edges.
Let cool on baking sheet for 3 or 4 minutes, then transfer to a wire rack to cool completely.
Store in an airtight container so you don't eat them all in one sitting!