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. Put dough in the refrigerator for an hour or so, or until the dough firms up.
Sprinkle your work surface and rolling pin with powdered sugar. Roll the dough out to a ¼ inch thickness.
Using a candy cane shaped cookie cutter, cut shapes into the dough. Place cookie dough shapes on a parchment paper lined cookie sheet and place in the freezer for 10-15 minutes.
Then, bake cookies in the oven at 375 degrees Fahrenheit for 8-10 minutes. The cookies should not brown completely, but the edges can be slightly browned (that’s a good indication it’s done). Cool on a wire rack.
For the Royal Icing
In a bowl of an electric mixer fitted with the whisk attachment, combine the powdered sugar, meringue powder, peppermint extractand water.
Mix for 7-10 minutes, until the ingredients are well blended and the icing has a matte finish. This is the base consistency. I usually add about 1 tsp more of water for a good outline icing (I use a 10 second rule) and add more water until I reach a 4-second icing for flood icing. This means that when you drizzle icing over the bowl of royal icing then the icing will flow back in with the rest of the icing in 4 seconds (10 second icing is the same but it will sink back in with the rest of the icing in 10 seconds). If you need to thin it out more then add more water. If you need to thicken it add more powdered sugar.
Outline the cookie using white icing (10 second icing) in a pastry bag fitted with a number 3 tip and then make diagonal lines on the cookie to section off the candy cane stripes.
Flood with thinned out white icing skipping every other section (4 second icing).
Then, take the green icing (4 second icing) in a pastry bag fitted with a number 2 tip and make a diagonal line in the middle of each white section. Let dry completely for at least four hours or overnight.
Once the white is completely dry (I'm seriously talking COMPLETELY dry otherwise the sprinkles part won't go so well), flood the remaining sections with red icing (4 second icing). Immediately after, sprinkle the red sanding sugar over the red sections. Shake off an excess. Dry completely.
*Instead of the gluten-free flours and xanthan gum, you can also use 2.5 cups of all-purpose flour.