Heat oven to 325 degrees. Prepare two baking sheets, lined with parchment paper.
Whisk flour, baking soda, cinnamon, and salt in a regular sized bowl.
Beat together butter and both sugars until fully incorporated and smooth.
Mix the wet ingredients - egg yolk, egg, and vanilla and add to the dry ingredients, scraping down the bowl until everything is incorporated. Do not overmix, which will yield a tough cookie.
Mix in the chocolate chunks gently, until dispersed evenly.
Separate mix into 18 portions and roll into rough balls. Pull the ball apart and stack them on the parchment - one on top of the other. Make sure the balls are about two inches apart. More is better.
Bake for 15-17 minutes, rotating the sheets once until the edges start to harden. Remove the sheets and allow the cookies to cool.