If you don’t have roasted pistachios, de-shell them and roast them in the oven at 200 degrees F for a couple of minutes.
Allow them to cool, and chop them in a food processor. The chopped pieces should be larger than the size of the sand.
In a mixing bowl, cream egg and sugar using an electric mixer. Beat the mixture until light and fluffy.
Add the butter and vanilla extract and mix until well combined.
Add flour, baking powder, and ground pistachio, and mix all the ingredients until you get a smooth dough.
Using a cookie scoop, scoop out dough balls on a lined baking sheet.
Sprinkle the cookies with the remaining crushed pistachios.
Place the cookies in a preheated oven and bake them for 10-12 minutes. Take the cookies out of the oven. Allow them to cool down on the baking sheet until they turn firm enough to be transferred to the cooling rack.