Preheat oven to 350°F.
Line baking sheet with parchment paper.
Beat butter and sugar until light.
Add egg and vanilla, mix well.
In another bowl, whisk flour, baking powder, and salt.
Combine dry mix into butter mix slowly.
Fold in chopped pistachios.
For filling, mix pistachio butter, sugar, cream, vanilla.
Scoop dough balls, flatten each slightly.
Add a teaspoon of pistachio filling inside.
Seal dough around filling carefully.
Place cookies on baking sheet.
Bake for 12–14 minutes until golden.
Cool on rack before serving.