Mix the flour, sugar, and baking powder in a large bowl.
Add the melted butter, vanilla essence, and eggs. Stir and knead until all combined into a thick dough.
Add the chocolate and pistachio butter, and knead into the dough. (This will make it somewhat sticky!)
Form into small balls, arrange on a greased baking sheet, and press gently to flatten. Make sure to leave enough space around each cookie, as they will spread to approximately double the size as they cook.
Bake for 10-15 minutes (until golden brown), then transfer to a wire rack to cool.