-
1
Put oven rack in middle position and preheat oven to 375F.
-
2
Pulse 1/2 cup nuts in a food processor until finely chopped, being careful not to process to a paste, then transfer to a large shallow baking pan.
-
3
Toast nuts, stirring every 2 minutes to prevent edges from burning, until pale golden, 6-8 minutes.
-
4
Cool completely in pan.
-
5
Whisk together flour and cornstarch in a bowl.
-
6
Beat together butter and sugar in a large bowl with an electric mixer at medium-high speed until pale and fluffy, about 3 minutes in a stand mixer or 5 with a handheld.
-
7
Add toasted ground nuts and salt and beat until combined.
-
8
Reduce speed to low, then add flour mixture and mix just until a dough forms.
-
9
Form dough into a rectangular block and roll out between 2 (12-inch long) sheets of parchment with a rolling pin into a 10- by 8-inch rectangle.
-
10
Chill dough in parchment on a baking sheet until firm, about 10 minutes.
-
11
Meanwhile, coarsely chop remaining 1/4 cup nuts.
-
12
Discard top sheet of parchment and sprinkle dough with coarsely chopped nuts.
-
13
Bake until golden, 14-16 minutes.
-
14
Transfer shortbread to a rack and cool completely, then break into rough shapes with your hands.
-
15
Keep cookies in an airtight container at room temperature 1 week.
-
16
For a neater cookie, cut shortbread, while still hot, into 8 (roughly 8- by 1 1/2-inch) cookies with a pizza/pastry wheel or sharp large knife.
