Whisk the flour, baking powder, and salt in a medium bowl. Set aside.

In a large mixing bowl, beat the softened butter and brown sugar with an electric mixer on medium speed until creamy and fluffy (about 2-3 minutes).

Add the egg and vanilla extract to the butter mixture and continue beating until well combined.

Gradually add the dry flour mixture to the wet ingredients, mixing quickly until a soft dough forms.

Fold in the finely chopped pistachios until evenly distributed throughout the dough.

Cover and chill the dough for one hour.

 Preheat your oven to 350°F  and line baking sheets with parchment paper.

Roll out the dough 1/4 inch thick.  Use your favorite cookie cutters to cut out shapes, and place them about 1 inch apart on the prepared baking sheets.

Bake cookies in the preheated oven for 10-12 minutes or until the edges are just beginning to turn golden.

Make sure you let the cookies cool completely on a wire rack before decorating.