In a large mixing bowl whisk together flour, cornstarch, cinnamon, baking powder, baking soda, and salt for 20 seconds, set aside.
In the bowl of an electric stand mixer fitted with the paddle attachment cream together butter and sugar until blended. Mix in egg then blend in sour cream, maple extract and vanilla extract.
With mixer set on low speed slowly add in flour mixture and mix until combined. Divide dough into 2 equal portions.
Place each portion on a sheet of plastic wrap and shape each into a round disk about 6-inches. Wrap with plastic wrap and chill 2 hours, or until firm enough to roll.
Preheat oven to 350 degrees during last 10 minutes of chilling.
Dust a work surface with a fair amount of flour. Remove one portion of dough from refrigerator, remove from plastic wrap and transfer to floured surface. Dust top with flour, then using a rolling pin, roll out just slightly thicker than 1/4-inch thickness.
Cut into 2 1/2-inch rounds. Transfer to an 18 by 13-inch baking sheet lined with parchment paper or a silicone baking mat.
Dust excess flour from scraps, press them together and re-roll dough and cut into rounds. Bake in preheated oven for 9 - 10 minutes until cookies are nearly set.
Repeat process with remaining dough in refrigerator. Once cookies are cool frost with the maple cinnamon frosting and store in an airtight container.
Add butter, powdered sugar, cinnamon and half and half to a medium mixing bowl. Using an electric hand mixer beat until well blended.
Add in maple extract and tint with brown gel food coloring if desired and whip until light and fluffy (if frosting is too thick you can add in a little more half and half, if it's too thin you can add a little more powdered sugar).
*To measure scoop flour using measuring cup then sweep top with a butter knife - no spoon and sweep here. Just be careful not to pack flour in when measuring.
Recipe source: Cooking Classy