Prep your pan and oven. Line a baking sheet with parchment paper. Preheat the oven to 325°F (165°C). A lower bake prevents over-browning and keeps that pale, classic shortbread look.

Cream the butter and sugar. In a large bowl, beat the softened butter and powdered sugar until smooth and slightly fluffy, about 1–2 minutes. Don’t overbeat; you want a creamy mixture, not whipped butter.

Add flavorings. Mix in vanilla and any zest or extracts you’re using. Stir just to combine.

Combine the dry ingredients. In a separate bowl, whisk together the gluten-free flour blend, rice flour (or cornstarch), salt, and xanthan gum if needed. This helps distribute the gum and salt evenly.

Bring the dough together. Add the dry ingredients to the butter mixture. Stir with a spatula or wooden spoon until a soft dough forms. It will look crumbly at first, then come together as you press it.

Rest briefly. Let the dough sit for 5–10 minutes. Gluten-free flours hydrate more slowly, and this short rest helps the dough roll and cut cleanly.

Shape or roll. You have two options: Classic rounds: Roll the dough between two sheets of parchment to about 1/4 inch (6 mm) thick. Cut into rounds or rectangles. Re-roll scraps gently.

Pan shortbread: Press the dough into an 8-inch (20 cm) square pan lined with parchment. Smooth the top and score into bars with a knife.

Dock and chill. Prick each biscuit with a fork to prevent puffing. If your kitchen is warm, chill the shaped dough on the baking sheet for 15 minutes to hold edges.

Bake. Bake for 16–22 minutes, depending on size, until the edges are just turning light gold and the tops look set. Shortbread should stay pale overall.

Finish and cool. While warm, sprinkle lightly with granulated sugar for sparkle, if you like. Cool on the sheet for 10 minutes, then transfer to a rack to cool completely. Shortbread firms as it cools.