01 - Preheat your oven to 350°F. Line a baking sheet with parchment paper.
02 - In a food processor, finely grind the pistachios. Add softened butter and powdered sugar; blend until creamy. Add the egg, vanilla, flour, and salt. Blend until smooth and well combined.
03 - Slice each croissant horizontally, leaving a small hinge so they don't separate completely.
04 - Brush the inside of each croissant with simple syrup to keep them moist during baking.
05 - Spread a generous layer of pistachio cream inside each croissant. Close and place on the prepared baking sheet.
06 - Spread a thin layer of the pistachio cream on top of each croissant. Sprinkle with chopped pistachios.
07 - Bake for 15-20 minutes, or until golden and the cream is set.
08 - Let cool slightly, then dust with powdered sugar before serving.