Cream the butter and sugar until it is light and fluffy.
Add the egg and vanilla and mix till combined.
Combine the remaining dry ingredients and whisk lightly to fluff up the flours as cassava flour likes to settle.
Slowly incorporate the dry ingredients into the wet and mix just until combined.
Shape the dough into a disk, wrap in parchment paper and allow it to chill about 30 minutes.
When you are ready to bake the cookies, preheat the oven to 350 degrees, place parchment paper on a baking sheet and set aside.
Roll the dough out to between ⅛ to ¼ inch thick, depending on if you like your cookies crunchier or softer. I like to place it between two pieces of parchment paper to help keep it from sticking.
Use your favorite cutters to shape the dough as you like and then place them on the prepared baking sheets about 1-2 inches apart. They don't spread, but they do puff a little as they bake.
Bake the cookies for 8-10 minutes. Allow the cookies to cool on the tray for about 2-3 minutes before transferring them to a cooling rack to cool completely.
Decorate them with royal icing or preferred icing of choice. Store in an airtight container for about a week.