Preparation / Directions:
Preheat oven to 325øF. and grease 2 baking sheets.
In a bowl with an electric mixer beat together butter and sugar until light and fluffy and beat in vanilla and zest.
Into another bowl sift together flour, salt, and baking powder, beat into butter mixture until just combined. Stir in nuts.
Roll level teaspoons of dough into balls and put 2-inches apart on baking sheets. (Alternatively, drop teaspoons of dough 2-inches apart onto baking sheets.) Bake cookies in batches in middle of oven until pale golden, about 18 minutes. Cool cookies on baking sheets 2 minutes and carefully transfer with a metal spatula to racks to cool completely. Cookies may be made 3 days ahead and kept in airtight containers.