Beat together the butter and sugar. Add the egg, egg yolk and vanilla extract and beat. Add the dry ingredients and beat until a dough forms.
Scoop and roll the dough in the cinnamon sugar. Be generous! You want them to be fully coated.
Bake the cookies at 350 degrees Fahrenheit for 12-14 minutes. 12 minutes will yield a softer, slightly underbaked cookie. 14 minutes will lead to a more thoroughly cooked, slightly crisp cookie.
Let the cookies cool on the baking sheet for 5 minutes, then transfer to a cooling rack to cool completely. Store the cookies in an airtight container. Enjoy!