13 tablespoons (182 g) unsalted butter, chopped
2 1/2 cups (350 g) all-purpose gluten-free flour
1 teaspoon xanthan gum (omit if your blend already contains it)
1/2 teaspoon kosher salt
1 teaspoon baking soda
2 teaspoons cream of tartar
1 1/2 teaspoons ground cinnamon
1 1/2 cups (300 g) sugar
2 eggs (120 g, out of shell) at room temperature, beaten
1 1/2 tablespoons ground cinnamon
3 tablespoons (36 g) sugar
First, brown the butter to make the cookies. Place the butter in a small, heavy-bottomed saucepan, and cook over medium heat, stirring constantly. First, the butter will melt, and then it will boil and foam. Continue to stir, and watch carefully. The protein solids will separate and drop to the bottom of the pan. As soon as you begin to smell a nutty smell, and begin to see a golden brown color start forming around the edges of the saucepan, remove the pan from the heat and continue to stir. Once the bubbles clear, you will be able to see whether the protein has begun to brown. If not, return to the heat briefly, stirring constantly, and remove once the butter has begun to brown. Continue to stir, as it will continue to brown off the heat. Pour the brown butter into a small, heat-safe bowl, and set it aside to cool until no longer hot to the touch.
In a large bowl, place the flour, xanthan gum, salt, baking soda, cream of tartar, cinnamon and sugar, and whisk to combine well. Add the eggs, and the cooled brown butter, and mix to combine. The dough will be thick, but soft. Divide it equally among two large pieces of unbleached parchment paper or plastic wrap. Roll each piece in the paper or plastic into a cylinder about 1 ½-inches in diameter, and roll to wrap tightly, twisting the ends to seal. Place the dough in the refrigerator until firm (at least 1 hour, and up to overnight).
When you are ready to bake the cookies, place the cinnamon and sugar for the topping in a shallow bowl or on a rimmed plate, and whisk to combine well. Line rimmed baking sheets with unbleached parchment paper and set them aside. Preheat your oven to 350°F.
Remove one piece of dough from the refrigerator, and slice it in cross-section into about 24 pieces, each about ½ inch thick. Press each disk of dough into the cinnamon-sugar topping mixture on both sides, and on the edges if you can manage. Place the cinnamon-sugar-covered disks of dough on the prepared baking sheets, about 2 ½-inches apart (the cookies will spread during baking).
Place the baking sheets, one at a time, in the center of the preheated oven and bake for 8 to 10 minutes, or until the cookies have spread to about double their original size, have taken upon something of a crackled appearance (as the cinnamon-sugar topping has spread) and appear set. Remove from the oven and allow to cool on the baking sheets until firm (about 5 minutes). Repeat with the remaining dough.