In a medium bowl, whisk together brown rice flour, white rice flour, potato starch, tapioca flour, cornstarch and xanthan gum. Set aside.
Cream butter and powdered sugar in a large bowl with an electric mixer.
Mix in egg, vanilla, almond extract and salt and beat until mixed well.
Gradually add in flour (1/2 cup at a time) and mix after each addition. Be sure not to over mix. I use the electric mixer for the first 2 cups of flour and then hand mix the last 1/2 cup.
Put dough in the refrigerator for about 20 minutes, or until the dough firms up slightly and is easier to roll out. You can also put it in the freezer but I would only do that for 10 minutes otherwise it’s very difficult to roll out. Sprinkle your work surface and rolling pin with powdered sugar.
Roll the dough out to a 1/4 inch thickness. Cut with cookie cutters. Place on a greased cookie sheet and put back in the freezer for 10-15 minutes.
Then, bake in the oven at 375 degrees Fahrenheit for 8-10 minutes or until cookie all the way through. The cookie should not brown, but the edges can be slightly browned (that’s a good indication it’s done). Cool on a wire rack.