For the cookies
2 cups (280 g) all-purpose gluten-free flour (I used Better Batter), plus more for sprinkling if necessary
1 teaspoon xanthan gum (omit if your blend already contains it)
3/4 teaspoon baking powder
1/4 teaspoon kosher salt
1/2 cup (100 g) granulated sugar
3 tablespoons (22 g) confectioners’ sugar
8 tablespoons (112 g) unsalted butter, at room temperature
1 egg (50 g, weighed out of shell) at room temperature, beaten
1 teaspoon pure vanilla extract
For the stained glass centers
About 16 Jolly Rancher or Life Savers hard candies, crushed into chunks
Pairs of cookie cutters in graduated shapes (suggested shapes: large and small stars, large and small Christmas trees, large and small hearts)
Preheat your oven to 350°F. Line rimmed baking sheets with unbleached parchment paper and set them aside. If you haven’t already, unwrap and crush the hard candies by placing a few of each color in a sealed plastic bag and tapping with a meat tenderizer or mallet. Don’t crush the candies too far in advance or the chunks will begin to stick to one another. Set the candies aside.
In a large bowl, place the flour, xanthan gum, baking powder, salt, granulated sugar, and confectioners’ sugar and whisk to combine well. Add the butter, egg, and vanilla, and mix to combine. The dough will be thick and relatively stiff, and you may need to squeeze it together with your hands to bring all of it together.
Roll the dough between two sheets of unbleached parchment paper or on a very lightly floured surface into a round a bit less than 1/3-inch thick. Using the larger of a pair of cookie cutters, cut out shapes from the dough and place them about 1-inch apart on a prepared baking sheet. Place the smaller, matching cookie cutter in the center of each shape and cut out a matching hole, removing the center. Fill the center of each hole with chunks of one color of the candy. Gather and reroll scraps and repeat the process with another pair of matching shapes. To make the cookies into a holiday decoration, poke a small hole (the smaller end of a chopstick works great) into the dough near the top of each cookie.
Place the baking sheet in the center of the preheated oven and bake until the cookies are set and the candies have melted completely, about 10 minutes, depending upon size. The melted candy will be bubbling, but will settle as the cookies cool. Allow the cookies to cool completely on the baking sheet. Peel the paper away from the back of the cookies to remove them from the baking sheets.