Cube your cold butter into small pieces and place it back in the freezer for at least 5 minutes—this is critical for achieving that tender, crumbly shortbread texture. While the butter chills, measure out your gluten-free flour, powdered sugar, and kosher salt. I always keep my mixer bowl in the freezer for a few minutes before starting because a cold bowl helps keep the butter cold during mixing, which results in a better final texture.
Combine the flour, powdered sugar, and salt in your mixer and blend on low speed for 1-2 minutes until evenly combined. Add the vanilla extract and the chilled butter cubes, then mix on low to medium speed for 3-5 minutes until the dough comes together into a smooth, cohesive mass. Stop mixing as soon as the dough forms—overmixing will develop gluten-like structures and make the cookies tough rather than tender. I prefer using a mixer because it keeps everything cold and ensures even distribution of butter throughout the dough.
Transfer the dough from Step 2 onto a piece of parchment paper and roll it out to approximately 3/4-inch thickness. Using cookie cutters or a knife, cut the dough into your desired shapes. Arrange the cut cookies on an ungreased baking sheet, spacing them about 1 inch apart. Transfer the baking sheet to the freezer for 30 minutes—chilling the shaped dough a second time ensures the cookies will hold their shape during baking and maintain their crispy texture.
After the dough has chilled for about 15 minutes, preheat your oven to 350°F so it reaches temperature by the time the cookies are ready. Once the full 30 minutes of freezing is complete, bake the cookies for 16-18 minutes until the edges turn golden brown—the centers may still look slightly underbaked, but they'll continue to firm up as they cool. Watch for the color change at the edges rather than relying solely on time, as oven temperatures vary.
Remove the baking sheet from the oven and let the cookies rest on the hot sheet for 10 minutes—this allows them to set without drying out. If the edges have spread and look slightly irregular, you can gently reshape them while they're still warm. Transfer the cookies to a wire cooling rack and allow them to cool completely, which will take another 10-15 minutes. This resting period is what gives shortbread its characteristic tender crumb.
If using chocolate, melt it in a microwave-safe bowl in 30-second intervals, stirring between each interval until smooth, or use a double boiler for gentle, even melting. Dip the bottom half or edges of each cooled cookie into the melted chocolate and place it on a parchment-lined baking sheet. Allow the chocolate to set at room temperature for 15-20 minutes, or place the sheet in the refrigerator for faster setting if you prefer. The chocolate adds richness and a lovely contrast to the buttery shortbread.
