In medium bowl – combine the almond flour, Carbquick, xanthan gum, salt, baking powder, and baking soda; mix well and set aside.
In a separate large mixing bowl, cream the butter, granular erythritol and stevia together. Add the eggs, mashed bananas, butttermilk, and vanilla and beat thoroughly.
Beat in the dry ingredients. Drop by rounded tablespoons full onto greased non-stick muffin top baking pans. Spread batter evenly into each muffin top circle.
Bake at in a preheated oven at 350° for about 12 minutes, or until the cakes spring back when pressed lightly in the center. Remove from the muffin top pans to wire racks. Cool completely before spreading with the filling.
Mix filling ingredients. Spread filling on one cake with generous amount of filling. Top with another cake, pressing down gently to distribute the filling evenly between the cakes. Repeat with all cookies to make 6 pies.