Preheat oven to 325°F (160 °C)
In a large mixing bowl, cream the butter and sweetener together.
Add vanilla and mix.
Sift the almond flour, all-purpose flour and cornstarch.
Add dry ingredients into wet, in intervals, using your mixer on low speed.
Turn out onto silicone mat and roll 1/4 to 1/3 inch thick.
Cut cookies into similar sizes, and place onto a parchment-lined baking sheet, approximately 2 inches apart.
Bake for approximately 20 minutes