Preheat the oven to 350 degrees F. Start by making the cinnamon sugar mixture (the filling). Combine room temperature butter, brown sugar, and cinnamon. Mix together and place in the freezer.
In a large mixing bowl, combine all purpose flour, baking soda, and kosher salt. Whisk together and set aside. In a separate bowl, make the cinnamon sugar by combining cinnamon and sugar and set aside.
Add room temperature butter to the bowl of a stand mixer fitted with the paddle attachment. Beat the butter on medium low speed for 2 minutes, then add sugar, light brown sugar, and cinnamon. Increase speed to medium speed and continue to mix for 3 minutes. Scrape down the sides of the bowl and then add the egg, egg yolk, and vanilla extract. Continue to mix, scrape down the sides of the bowl once more and mix for an additional minute.
Add flour mixture and mix until just combined and all ingredients are fully incorporated.
Use a medium cookie scoop (about 2 1/2 tbsps of dough) to scoop out a cookie dough ball. Roll into a ball. Remove the cinnamon sugar filling from the freezer and scoop out two teaspoons of the filling. Pinch the filling into about 3-4 crumbly pieces and press into the cookie dough balls. Roll again into a ball and then place into the cinnamon sugar to coat.
Place onto a baking sheet lined with parchment paper, baking about 5-6 cookies at a time, spacing about 2-3 inches apart (these cookies will spread). Bake for 11-12 minutes.
Use the opening of a small bowl or circular container and swivel it around the cookie to create that perfect circular shape. Let the baked cookies chill on the baking sheet for at least 5 minutes, then place on a wire rack to cool completely (or until you're ready to eat them)
Notes
Tips
Set a timer for these cookies do not let them go past 12 minutes in the oven or else they'll burn. While recipe testing, I went upstairs to change the baby's diaper and let them bake for 1 minute longer than I wanted and boom - they were burnt and crispy. Don't burn these chewy cookies!
Use a cookie scoop to make sure all of the cookies are the same size!
Please. Please. Please measure your ingredients properly! It can literally make or break a recipe! Measuring your ingredients, especially your dry ingredients, can prevent you from adding too much flour which can really alter the recipe. I prefer to measure everything in grams, which you can do by converting the recipe card to metric measurements. However, if you prefer to measure in cups, just be sure to fluff your flour up prior to scooping it out of the container.
Lastly - these with vanilla ice cream is out of this world. Thank me later!