Preheat oven to 180°C (350°F).
Combine melted butter and saffron. Mix and set aside.
In a separate bowl, combine sugar and eggs. Mix.
Add saffron and butter mixture. Mix.
Add flour and baking powder. Mix thoroughly.
Add chopped pistachios. Mix until a dough starts to form. It's ok to use your hands at this point.
Form a ball of dough and cut in into four equal portions.
Form a log for each portion (about 27-29 cm long).
Place the logs on a tray, lined with a baking sheet.
Place the tray in the middle of the oven for 15 minutes.
Take the tray out of the oven and adjust the oven into 120°C (250°F).
Let the logs cool for 15 minutes.
Once properly cooled, cut logs into equal portions (about 1 & 1/2 cm width each).
Place the cookies back on the tray lined with baking sheet. Place the tray back in the oven for 30 minutes.
Take the tray out of the oven and turn the cookies to the other side. Place the tray back in the oven for 30 more minutes.
Take the cookies out of the oven and let cool.