Preheat your oven to 350°F. Grease well a standard 12-cup muffin tin and set it aside.
In a large bowl, place the flour blend, xanthan gum, baking powder, salt, confectioners’ sugar and granulated sugar, and whisk to combine well.
Create a well in the center of the dry ingredients and add the butter, shortening, egg and vanilla, mixing well to combine after each addition. The dough should come together and will be soft.
Roll the dough into balls about 1 1/4-inches in diameter, and press into disks about 1/4 inch thick. Place one disk into each of the prepared wells of the muffin tin, and press the bottom of a juice glass right into the center of the dough, forcing the dough evenly up the sides of each well.
Remove the glass. If any of the cookie has reached above the lip of each well, press it down to avoid its burning in the oven. Using a toothpick, poke 3 evenly spaced holes in the bottom of the dough in each well.
Place in the center of the preheated oven and bake for 12 minutes, or until the edges are very lightly golden brown and the center of each cup springs back when pressed gently.
Remove from the oven and allow to cool for 5 minutes before carefully transferring the cups to a wire rack to cool completely. Repeat with the remaining few pieces of cookie dough.
Make the filling.
Transfer 2 tablespoons of the cream to a small bowl and set it aside.
In the bowl of a stand mixer fitted with the whisk attachment or a large bowl with a handheld mixer, place the remaining cream and beat on medium-high speed until soft peaks form.
Add the confectioners’ sugar, and continue to beat until stiff, glossy peaks form.
Transfer the whipped cream to a separate, large bowl and place in the refrigerator to chill. In the same bowl, place the cream cheese, vanilla, salt and reserved 2 tablespoons cream.
If using a stand mixer, switch to the paddle attachment (if using a handheld mixer, the beaters will be fine) and beat on medium-high speed until the cream cheese is light and fluffy.
Remove the whipped cream from the refrigerator and add the beaten cream cheese mixture.
Using a separate, handheld whisk, whisk the mixture together until light and fluffy, adding more cream by the teaspoonful as necessary to create a smooth mixture.
Fill the cookie cups.
Transfer the filling to a piping bag fitted with a large open tip and pipe the filling into the wells of the prepared cookie cups. Decorate with berries or sprinkles, if desired.
Place the filled cups in the refrigerator to chill until set (about 2 hours) or serve as is.