"Rock" cookies with a craggy, sugar-crusted exterior are a rustic Mexican sweet. This family-friendly treat is a crunchy, sweet, traditional bakery cookie with charming texture.
Preheat the oven to 375°F (190°C) and line a baking sheet with parchment paper.
In a medium bowl, whisk together the flour, baking powder, salt, and ground cinnamon to combine dry ingredients thoroughly.
In a separate large bowl, beat the unsalted butter and granulated sugar until light and fluffy, about 2-3 minutes on medium speed.
Add the egg and vanilla extract to the creamed butter mixture and mix until fully incorporated, scraping down the sides as needed.
Gradually add the dry ingredients to the wet mixture, alternating with the milk. Mix just until a thick dough forms; do not overmix.
Scoop dough into rough mounds (about 2 tbsp each), roll tops in coarse sugar, and arrange on baking sheet, leaving space between each.
Bake for 16-18 minutes, or until cookies are golden with a craggy, crisp exterior. Avoid overbaking for the best texture.
Cool cookies on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.