In a standing mixer combine the butter & sugars. Mix on high for 2 minutes until creamed. The mixture will be lighter in color and texture.
Add eggs & vanilla extract stir until combined.
In a separate bowl combine flour, baking soda, fine sea salt, cinnamon & cornstarch.
Pour 1/2 the mashed bananas into the standing mixture, stir until combined. Pour half of the flour mixture into the standing mixture, stir until combined. Repeat once until all the banana & flour mixture is fully combine in the standing mixer.
Scoop the cookies onto light metal cookie sheets lined with parchment paper
Sprinkle cinnamon sugar mixture on top of the cookie dough. You can use the ratio of cinnamon & sugar that you like.
Bake the cookies for 11-12 minutes
Remove and allow the cookies to sit on the baking sheet for 10-15 minutes before you remove and allow them to finish cooling.