Whisk flour, espresso, and salt in a bowl. Put butter and sugar in the
bowl of an electric mixer fitted with the paddle, and mix on
medium-high speed until pale and fluffy. Mix in vanilla. Add flour
mixture; mix on medium-low until dough comes together. Shape
into a disk, and wrap in plastic. Refrigerate 30 minutes.
Preheat oven to 350 degrees. Let dough stand at room temperature
10 minutes. Roll between sheets of parchment to 1/8 inch thick.
Cut out rounds with a 1 1/8-inch cutter; space 1/2 inch apart on
baking sheets lined with parchment. Reroll scraps; cut out. Freeze