Steps Sift together the flour, baking soda, baking powder and salt into a bowl; set aside.
In a large bowl Combine the butter, sugar, orange zest and vanilla. Using an electric mixer set on high speed, beat until light and fluffy. Mix in the eggs one at a time, beating well after each addition. Reduce the speed to low, add the pistachios and mix in. Add the flour mixture and mix just until incorporated. Cover and refrigerate until well chilled, about 1 hour.
Preheat an oven to 350ºF. Butter and flour a large baking sheet.
Divide the dough in half. On a lightly floured surface, using lightly floured hands, roll each half into a log 1 1/2 inches in diameter. Arrange the logs on the prepared baking sheet, spacing them 5 inches apart.
Bake until light brown and firm to the touch, about 30 minutes (the logs will spread during baking). Remove from the oven and let cool slightly on the baking sheet. Leave the oven set at 350ºF.
Using a spatula, carefully transfer the logs to a work surface. Using a serrated knife, cut on the diagonal into slices 3/4 inch thick. Arrange the slices, cut side down, on the baking sheet and bake until golden brown, about 15 minutes. Transfer the cookies to wire racks to cool. Store in an airtight container at room temperature for up to 2 weeks.
Makes about 3 dozen