01 - Preheat oven to 350°F. Line a baking sheet with parchment paper.
02 - Finely grind pistachios in a food processor. Add softened butter and powdered sugar; blend until creamy. Incorporate egg, vanilla, flour, and salt. Process until smooth and fully combined.
03 - Slice each croissant horizontally, keeping a small hinge on one side to prevent complete separation.
04 - Lightly brush the interior of each croissant with simple syrup to maintain moisture during baking.
05 - Spread a generous layer of pistachio cream inside each croissant. Close and arrange on the prepared baking sheet.
06 - Apply a thin layer of pistachio cream atop each croissant. Sprinkle evenly with chopped pistachios.
07 - Bake for 15 to 20 minutes until golden brown and the filling is set.
08 - Allow to cool briefly, then dust with powdered sugar before serving.