In a small mixing bowl, whisk together the almond flour, arrowroot flour, tapioca flour, baking powder, and salt.
In a medium mixing bowl, add the butter and sugar. Using a hand held mixer, cream the butter and sugar together on medium speed until light a creamy. Add the egg yolk and vanilla extract and continue to beat until fully incorporated. Note - See Notes on using a stand mixer.
Sprinkle about half of the dry ingredients over the wet ingredients and mix on low until just incorporated. Add the remaining dry ingredients and mix until a dough forms. Note - The dough starts off crumbly and may seem too dry. Continue to mix and a dough will eventually for - this may take a couple minutes.
Pour the cookie dough into the center of a piece of plastic wrap and shape into a disc. Wrap the dough tightly in the plastic wrap and refrigerate for at least 1 hour, or even overnight.
When ready to bake the cookies, preheat the oven to 350F degrees and adjust the oven rack to the middle position. Line a baking sheet with a piece of plastic wrap.
Very lightly flour your work surface with arrowroot flour. Roll the chilled dough to your desired cookie thickness. I roll my cookies to about 1/4 inch thick. Cut out the cookies using cookie cutters and place on the baking sheet. Repeat as necessary. Note - The number of cookies you yield from the recipe will depend on how thick you roll the dough and the size of cookie cutters you use.
Bake the cookies for 8 to 10 minutes, or until the edges start to turn a light golden brown. Cool the cookies on the baking sheet set on a wire cooling rack for 5 minutes. Then transfer the cookies to the wire rack to cool completely.