In a medium bowl, combine all of the dry ingredients for the cookie dough (do not include the cinnamon filling here).
In the bowl of a standmixer, combine butter and sugars. Beat on medium until light and fluffy, about 6 minutes. Scrape down the sides of the bowl and mix again for 1 minute.
Add in egg and vanilla, scraping sides of the bowl before the addition. Mix until combined.
Add in all dry ingredients and mix for 1 minute or until thoroughly combined. Dough will be thick.
Into the standmixer, drop in the frozen cinnamon filling balls, Mix very quickly in standmixer until JUST combined. Too much filling as compared to dough will cause the cookies to spread. Cover and let dough rest for in the refrigerator at least 30 minutes.
Prepare a cookie sheet with parchment paper Scoop cookies into 2.5 tablespoon sized balls about 3 inches apart.. Have a circular cookie cutter handy to help form dough into perfect circles.
Preheat oven to 350F. Bake cookies for 11-15 minutes OR until the edges are set. Don't worry if cookies look like they are spreading and no longer circular, let them cook through and when you remove them from the oven, use the circle cookie cutter to form them into a circle shape. Let rest.