Chocolate Oreo Espresso Thins

Makes about 4 dozen

The secret to the super-crisp texture here is cutting the dough into
very thin rounds; coarse sanding sugar on top adds to their crunch.
Holiday Cookies 2005, Special Issue Holiday 2005

1 1/2 cups all-purpose flour
1/2 cup unsweetened Dutch-process cocoa powder
1 1/2 teaspoons instant espresso powder
1/2 teaspoon coarse salt
1 cup (2 sticks) unsalted butter, softened
1 cup confectioners' sugar
1 teaspoon finely grated orange zest
1 teaspoon pure vanilla extract
Coarse sanding sugar, for sprinkling

Sift together flour, cocoa powder, espresso powder, and salt into
a medium bowl; set aside.
Put butter, confectioners' sugar, orange zest, and vanilla in the
bowl of an electric mixer fitted with the paddle attachment. Mix on
medium speed until pale and fluffy, about 3 minutes. Reduce speed to
medium-low, and gradually add flour mixture until just combined.
Transfer dough to a 12-by-16-inch piece of parchment; shape into a
log. Roll in parchment to 1 1/2 inches in diameter, pressing a ruler
along edge of paper at each turn to narrow the log and force out air.
Transfer in parchment to a paper towel tube; chill at least 2 hours or
overnight.
Preheat oven to 350 degrees. Cut log into 1/4-inch-thick slices;
transfer to baking sheets lined with parchment paper. Brush tops with
water; sprinkle with sanding sugar. Bake until set, 15 to 17 minutes.
Cool on sheets on wire racks. Store in airtight containers at room
temperature up to 1 week.