Mix dry ingredients in a bowl – all purpose flour, ground pistachios, salt, baking powder.
In a food processor, take butter and sugar. Pulse it few times to mix them and add vanilla extract and pistachio butter if using. Again, pulse for few times. You can easily use hand blender too.
Add dry ingredients in the butter mixture along with 2 tbsp milk and pulse and make sure it is mixed well.
Transfer the cookie dough on a surface and make sure to mix it with hands if its crumbly. Cover it and chill it for 1-2 hours or overnight. Chilled dough is easy to work with and its not sticky.
Remove the chilled dough for 10 mins or so. Divide it into equal portions using an ice cream scoop or measuring spoon. Roll them into balls. Chill them again for 10 minutes. Pre heat the oven to 350 F.
Sugar Coating - Roll each ball into granulated sugar first and then in confectioners’ sugar. Make sure they are rolled quite a bit in raspberry confectioners’ sugar. Bake the cookies for 15-17 minutes in a pre-heated oven at 350 F on parchment lined baking sheet.
If the cookies do not spread by minute 8-minute mark, remove them from the oven and lightly bang the baking sheet on the counter. I used spatula to slightly press them down. Return to the oven to continue rest of the baking.
Let them cool for few minutes on the baking sheet, then transfer them to a cooling rack to cool completely. Once completely cooled, store them in a container covered and it stays fresh upto a week.