Chef John's Rosemary Shortbread Cookies

Preheat oven to 300 degrees F (150 degrees C). Line a baking sheet with parchment paper.

Place cold butter, sugar, rosemary, salt, and vanilla extract in bowl. Combine with the back of a spatula or spoon, slowly incorporating ingredients together until butter has softened somewhat and ingredients come together.

Pour flour into bowl with butter mixture. Flour your hands to then incorporate flour into the butter, using fingertips and rubbing mixture together until flour-y crumbs become buttery crumbs, 1 to 2 minutes. Press mixture together into a dough ball.

Transfer dough to lightly floured work surface. Press dough into a disk, then into a 1/2-inch thick rectangle. Cover with a piece of plastic wrap. Flatten dough to 1/4-inch thick using a flat pan or rolling pin. Reshape into a rectangle.

Cut dough lengthwise into 5 even strips about 1 inch wide, trimming extra dough if necessary. Cut each strip into 6 evenly sized squares. (You can roll out scraps to form more cookies if necessary). Transfer cookies to prepared baking sheet. Sprinkle each cookie with about a pinch of sugar. Using a fork, poke 4 rows of holes into each cookie.

Bake in preheated oven until golden brown, about 50 minutes.

Cool cookies 10 minutes on sheet; transfer cookies to rack to cool completely.