Preheat oven to 350 degrees. In a mixing bowl whisk together, all-purpose flour, corn flour, baking powder, baking soda and salt, set aside. In the bowl of an electric mixer whip together butter and sugar until light and fluffy about 3-4 minutes. Stir in egg and egg yolk. Mix in sour cream, vanilla and lemon juice. Slowly add in dry ingredients and mix until well incorporated. Form dough into balls by the heaping tablespoon fulls then place on cookies sheets and flatten dough balls evenly to about 1/2" with your hands. Bake in preheated oven for 9-11 minutes. Allow to cool completely before frosting with Honey Butter Frosting.
Honey Butter Frosting
In a large mixing bowl, using an electric mixer, whip together all ingredients until light and fluffy about 1 - 2 minutes.
Recipe Source: Cooking Classy
Notes
*You can usually find this in the health foods section or gluten free section of the grocer or supermarket. If you can't find it there you can also purchase it online here.