Flaky cinnamon shortbread cookies are a traditional Mexican Christmas confection. This family-friendly treat is a crumbly, aromatic, buttery cookie perfect for the holiday season.
Cream together unsalted butter and confectioners' sugar with an electric mixer on medium speed until light and fluffy, about 4 minutes.
Add egg yolk and vanilla extract to the butter mixture; beat until fully incorporated and smooth.
In a separate bowl, whisk together all-purpose flour, ground cinnamon, and salt, then gradually add dry mixture to wet ingredients, mixing on low speed until a soft dough forms.
Divide dough in half, shape into disks, wrap in plastic, and chill in the refrigerator for at least 1 hour for easy handling.
Preheat oven to 350°F (175°C). On a lightly floured surface, roll dough to 1/4-inch thickness, cut out shapes with cookie cutters, and arrange on a parchment-lined baking sheet.
Bake for 14–16 minutes until edges are barely golden; avoid overbaking to maintain a tender, crumbly texture.
While still warm, toss cookies gently in granulated sugar mixed with cinnamon for a fragrant coating. Cool completely on a wire rack before serving.