Preheat oven to 350F. Line a quarter sheet pan or 9x13 baking dish with parchment paper, leaving a 1-inch overhang on all sides.

In a medium bowl, whisk together the baking powder, salt, gluten free flour blend and xanthan gum (if using) until combined. Set aside.

In a large bowl, add softened butter and granulated sugar. Cream together until light and fluffy, about 2 minutes.

Add in the egg and vanilla and mix until combined.

Then gradually mix in the flour mixture, until no white streaks remain.

Bake the cookie at 350F for 15-18 minutes, until the cookie is lightly browned, being sure not to over bake. Let cool completely.

Add the softened cream cheese and butter in a medium size bowl.

With an electric mixer, cream the cream cheese and butter until smooth.

Then, stir in the vanilla extract until combined.

Gradually add in the powdered sugar, mixing in between each addition, until combined. You can add additional powdered sugar until you reach your preferred consistency.

When the cookie is completely cool, pour the cream cheese frosting onto the cookie.

With an offset spatula or the back of a spoon, smooth the frosting to cover the entire cookie.

Starting with the blueberries, make a box in the upper left hand corner of the cookie. I did a row of 7 blueberries across and 5 blueberries down.

Next, create a line along the top with the sliced strawberries, letting them slightly overlap.

Leave about an inch space of white frosting, and then create another horizontal line, this time with the raspberries.

Continue alternating lines of strawberries and raspberries (leaving white space in between) until you reach the bottom of the cookie cake.

Store in the refrigerator until ready to serve.