Step 1

Preheat your oven to 375°F. Line rimmed baking sheets with parchment paper and set them aside.

Step 2

In a large bowl, place the butter, 3/4 cup granulated sugar, egg, and vanilla. Beat with a handheld mixer until light and fluffy.

Step 3

Add the flour, xanthan gum, salt, 3/4 teaspoon ground cinnamon, baking soda, and cream of tartar to the wet ingredients, mixing to combine after each addition.

Step 4

Divide the dough into 18 pieces of roughly equal size. Roll each piece of dough between your palms until it forms a ball, and then press into a disk.

Step 5

Combine the cinnamon and sugar for the rolling mixture in a small bowl. Toss each disk in the cinnamon-sugar mixture until it is well-coated. Allow the dough to sit for 5 minutes to absorb the coating.

Step 6

Roll each ball of dough in the cinnamon-sugar mixture once more, and arrange them about 2 inches apart on the lined baking sheets.

Step 7

Place the rimmed baking sheets in the center of the preheated oven and bake for 8 to 10 minutes, or they are either pale but flat (8 minutes), or a tiny bit crisp around the edges (10 minutes).

Step 8

Cool on the baking sheets for about 10 minutes, then transfer to a wire rack to cool completely.