1 1/2cupsfinely ground white rice flour(6 ounces; 170 grams)
1/2cupsweet rice flour(2 ounces; 56 grams)
1/2cuptapioca starch(2 ounces; 56 grams)
1/2teaspoonsalt
1/8teaspoonxanthan gum
2sticksunsalted butter, at room temperature(1 cup; 8 ounces; 226 grams)
1/2cup powdered sugar(2 ounces; 56 grams)
zest of one lemon, finely chopped
2tablespoonsfreshly squeezed lemon juice
4cupspowdered sugar(16 ounces; 453 grams)
Instructions
Preheat oven to 350 °F. Line rimmed baking sheet with parchment paper.
In small mixing bowl, whisk together dry ingredients. Set aside. In bowl of stand mixer or medium mixing bowl, cream together butter, 1/2 cup powdered sugar, and lemon zest until a thick paste forms about 30 seconds. (Use medium-high speed on a handheld mixer or medium speed on a stand mixer.) Stop mixer and scrape down bowl. Turn mixer on and cream for another 15 seconds.
Add dry ingredients and mix until dough forms, about twenty seconds. Add lemon juice and mix until combined. Chill dough for twenty minutes.
Scoop dough, about one tablespoon each, and roll into ball. Place dough on baking sheet and press dough ball down slightly. Return remaining dough to refrigerator.
Bake until cookies are set and slightly cracked, about 18-20 minutes. These cookies don't really darken during baking. While cookies are baking, fill an 8x8-inch pan with 4 cups powdered sugar. Set aside
Remove cookies from oven. Allow cookies to set for two minutes. Carefully transfer cookies to the pan of powdered sugar with a spatula. Bury cookies in the sugar and allow to cool.
Repeat with remaining dough. Remove cooled cookies from powdered sugar and shake off excess sugar.