Combine water, sugar, cardamom, rose water, and saffron in a saucepan; bring to a boil. Reduce heat and simmer until consistency is syrupy.

Mix milk powder, flour, and baking soda in a bowl until well-combined. Slowly mix in butter and yogurt until dough comes together. Let gulab dough rest for 5 minutes. Shape into smooth balls the size of pennies.

Heat oil in a deep-fryer or large saucepan to 350°F (175°C). Test the temperature of the oil by dropping in a small piece of dough. When it sits at the bottom for 1 minute before coming to the surface, the oil is ready.

Fry 4 gulab balls at a time, stirring carefully, until dark golden brown on all sides, about 2 minutes per batch. Drain on a paper-towel-lined plate. Repeat with remaining gulab.