Combine the rice flour and sugar and add to a saucepan containing the milk. Slowly bring to a boil whisking vigorously for about 2 minutes, taking care not to scorch the mixture. Add cardamom and saffron and continue stirring for 1 more minute. Remove from heat, and add rosewater. Pour pudding into individual serving glasses and let cool completely. Refrigerate for about 2 hours. Top surface completely with finely chopped pistachios and serve.