1 1/2 cups (210 grams) unbleached all-purpose flour
1/2 cup (65 grams) cornstarch
3/4 teaspoon kosher salt
1/2 teaspoon baking powder
Procedure:
1. Using a stand mixer fitted with the paddle attachment (or handheld
mixer or a wooden spoon), cream the butter on medium speed for
about 2 minutes, or until light and pale. (This step will take 3 to 4
minutes if using a handheld mixer and about 5 minutes if using a spoon.)
Add the sugar and beat on medium speed for 3 to 4 minutes, or until
light and fluffy. Stop the mixer a few times and use the rubber spatula to
scrape the sides and bottom of the bowl and the paddle to release any
clinging butter or sugar. On low speed, add the egg yolk and rosemary (in
my case: thyme and lemon zest) and beat for about 1 minute, or until
thoroughly combined.
2. In a small bowl, sift together the flour, cornstarch, salt, and baking
powder. On low speed, slowly add the flour mixture to the butter-sugar
mixture and then mix just until the flour mixture is totally incorporated
and the dough is evenly mixed. Stop the mixer several times to scrape the
bowl and the paddle to free any trapped flour mixture.
3. Scrape the dough onto a piece of plastic wrap, and wrap the dough in
the plastic wrap, pressing down to form a disk about 8 inches in diameter
and 1 inch thick. Refrigerate the dough for about 20 minutes, or until it is
firm enough to roll out.
4. Position the rack in the center of the oven, and heat the oven to
325 degrees F.
5. On a floured work surface, roll out the dough into a rectangle about
12 inches by 10 inches and 1/4 inch thick. Using a sharp knife, cut the
dough into 12 to 15 uniform pieces -- rectangles, triangles, or cookie-
cutter shapes -- and arrange them on a baking sheet, spacing them about
2 inches apart. (At this point, the cookies can be tightly wrapped and
frozen for up to 2 weeks. Bake as directed directly from the freezer. You
may need to add a few minutes to the baking time.)
6. Bake for 18 to 20 minute, or until the cookies are medium to golden
brown all the way through. Let cool on the baking sheet on a wire rack
for 15 to 20 minutes, then transfer to a wire rack to cool completely.
7. The cookies can be stored in an airtight container at room temperature
for up to 4 days.