Take a cheesecloth or muslin cloth and place it over a strainer.
Pour the yogurt into the cloth and let it drain for 3-4 hours in the refrigerator. This will make the yogurt thick and creamy.
Once the yogurt has drained, remove it from the cloth and transfer it to a mixing bowl.
Add powdered sugar and mix well until the sugar dissolves completely.
Soak the saffron in warm milk for a few minutes and then add it to the yogurt mixture.
Whisk the yogurt mixture using hand blender until looks smooth and glossy texture.
Add cardamom powder, chopped pistachios, almonds and mix well.
Chill the shrikhand in the refrigerator for a few hours.
Serve the chilled Kesar Pista shrikhand in bowls and garnish with slivered nuts and rose petals (optional).