- 2 sticks (8 ounces) unsalted butter, softened
- 1 1/2 cups confectioners' sugar
- 1/2 cup cornstarch
- 1/2 teaspoon pure vanilla extract
- 1 1/2 cups all-purpose flour
- Preheat the oven to 350°. Line a large baking sheet with parchment paper. In a food processor, pulse the butter with 1/2 cup of the confectioners' sugar until combined. Add the cornstarch, vanilla and flour and process until a soft dough forms. Transfer the dough to a work surface and divide it into 4 equal pieces.
- On a lightly floured work surface, roll each piece of dough into a 12-inch rope. Cut each rope into 12 pieces and roll each piece into a ball. Transfer the balls to the baking sheet; they won't spread much. Bake the cookies on the center rack of the oven for about 22 minutes, until the bottoms are golden but the tops are still pale.
- Sift the remaining 1 cup of confectioners' sugar into a bowl. Add 12 warm cookies to the bowl at a time and toss to coat. Transfer the cookies to a clean baking sheet. While the cookies are still warm, poke 4 shallow holes into each one with a toothpick or skewer to make a buttonhole pattern. Let the cookies cool completely before serving or storing.
The cookies can be stored in an airtight container for up to 1 week.