Sweetened Yogurt with Saffron and Pistachios (Shrikhand)

Cut 3 layers of cheesecloth into a 12" x 24" square. Put yogurt in middle of cheesecloth, bring up ends, and tie with kitchen twine. Tie cheesecloth-bound yogurt to the handle of a wooden spoon; set wooden spoon over a bowl. Chill yogurt and let drain overnight to a thicker consistency. Combine saffron and milk and let steep for 30 minutes. Put drained yogurt into a bowl; stir in saffron mixture and sugar. Divide shrikhand between 6 small bowls and garnish with cardamom and pistachios.