• Preheat oven to 325 degrees F.
• Cream butter until light and fluffy.
• Slowly add confectioner's sugar, scraping down sides. If dough is too sticky, add a little more flour. Add 3/4 chopped pistachios and zest of orange.
• Mix flour and kosher salt together and add flour to butter mixture, mixing just until incorporated. Don't over-mix!
• Flatten dough into a round or rectangular disk and chill 30 minutes. This is especially important on a warm day.
• Lightly flour a board and roll out the shortbread dough to a thickness of about 1/3 to 1/2". Cut into shamrock shapes, or if making fingers, roll into a large rectangle and cut into rectangles approximately 1" x 2".
• Bake on a silpat or parchment paper in center of oven for 20-25 minutes, or until a pale golden color.
• If desired, sprinkle shortbread with sanding sugar immediately.
• Cool completely on a wire rack
• Store shortbread in an airtight container.

Chocolate Dipped Shortbread

• Melt 1/4 cup chopped chocolate or chocolate chips over a double boiler or in the microwave for about 45 seconds, stirring occasionally.
• Dip one end of each shortbread finger in melted chocolate, then into 1/4 cup finely chopped pistachios.