In a small mixing bowl whisk together cake flour, all-purpose flour, baking powder, cream of tartar and salt. With mixing speed on low, gradually add dry ingredients until no flour pockets remain. Place dough in an air tight container and refrigerate for at least 3 hours.

Preheat oven to 375 degrees. Line two baking sheets with parchment paper or a Silpat baking mat, set aside.

Using a large cookie scoop (#20- approximately 3½ tbsp.), create balls of dough, lightly roll on a floured surface so that it covers the ball of dough completely. Press each ball of dough flat so that it is ½" thick and about 2½ wide. Place 6 cookies onto each prepared baking sheet. Place in oven and bake for 10-11 minutes (the cookies will still look soft in the centers, do not over bake) or until the cookies become firm on the edges. Remove and allow to cool for 3 minutes before transferring to a wire rack to cool completely.

Meanwhile, to make the frosting, beat all of the ingredients with a mixer until smooth.

To assemble, spread the frosting or Nutella on top of the cooled cookies, then layer with fruit.