'Nilla Wafers

1 1/3 cups all-purpose gluten-free flour
1/2 teaspoon xanthan gum
1/2 teaspoon baking powder
Dash (1/8 teaspoon) baking soda
1/2 teaspoon kosher salt
1/2 cup (8 tablespoons) unsalted butter, at room temperature
1/2 cup packed light brown sugar (in a pinch, dark brown sugar will do)
1 extra-large egg (or the biggest large egg in the dozen), at room temperature
4 teaspoons pure vanilla extract
2 tablespoons milk

1. Preheat the oven to 325 degrees Fahrenheit. Line rimmed baking sheets with parchment paper and set them aside.
2. In a large mixing bowl add the flour, xanthan gum, baking powder, baking soda and salt, and whisk to combine. Add the butter, sugar, egg, vanilla and milk, mixing well with a hand mixer after each addition. The batter should be thickened, but thin enough to be piped through a plain pastry piping tip.
3. Either scoop dough by the level tablespoonful, or pipe an equivalent amount through a pastry bag fitted with a plain piping tip or plastic bag with corner cut out (for more consistent cookie sizing), onto the prepared baking sheets. The mounds of dough should be spaced about 1 inch apart. They will spread, but not a lot. If you have piped the dough, with wet fingers, gently flatten the top of each raw cookie if anything is sticking up.
4. Chill the raw cookies on the baking sheet in the freezer for a few minutes until firm.
5. Once they are firm, place the baking sheet in the center of your preheated oven and bake for between 15 and 20 minutes, or until the cookies are nice, uniform brown color — like they came right out of that brown wax paper bag in that Nabisco box.
Cool a few minutes on the baking sheets before moving to a wire rack to cool completely.

Original recipe from Nicole @ Gluten Free on a Shoestring: http://glutenfreeonashoestring.com/nilla-wafers/