For the shortbread: Preheat the oven to 325 degrees F. Pulse
the pistachios until finely ground in a food processor. Remove.
Combine the butter, confectioners' sugar
, lime juice, lime
and salt in the food processor
and process until well combined. Add the flour and pistachios and pulse to combine.
Pat the dough
into an 8- by 8-inch baking pan and smooth the top to flatten evenly. Pierce the dough all over with a fork. Score
into 4- by 4-inch pieces using a paring knife, making a total of 16 pieces.
Bake until the cookies are set and golden brown, 25 to 30 minutes. Immediately cut the shortbread through the scored lines; cool in the pan on a wire rack.
For the glaze
: Mix together the confectioners' sugar and lime juice in a small bowl. Spread the glaze over the cooled cookies
and sprinkle the lime zest
over the top.