Combine milk and sugar together in a saucepan; bring to a boil.
Whisk water and cornstarch together in a bowl until smooth; stir into boiling milk. Cook milk mixture over medium heat until thickened to the consistency of cake batter, 15 to 20 minutes. Remove saucepan from heat and stir cream, rose water, and cardamom into milk mixture.
Refrigerate milk mixture until completely cooled, 2 to 4 hours.