Dissolve ground saffron in 2 tablespoons of boiling water and set aside (click for How to Use Saffron).
In a small bowl, sprinkle the gelatin over 5 tablespoons cold water and let stand 5-6 minutes.
Meanwhile combine the heavy cream, milk, sugar and dissolved saffron in a small saucepan over medium heat, stirring until sugar is dissolved. Remove the saucepan from the heat and add the vanilla extract and gelatin. Whisk together gelatin and cream mixture until thoroughly incorporated.
Pour into individual serving dishes and chill for at least 2 hours or until set. Garnish the Saffron Panna Cotta with pistachios and serve.