Whisk water, rose water, milk powder, sugar, and cornstarch together in a saucepan until smooth. Place over medium heat, stirring with a wooden spoon, and cook until it begins to boil; cook at a boil for 2 minutes. Remove from heat immediately; stir a few times to help it cool.
Divide the mixture between 8 small serving glasses; refrigerate until set, about 2 hours.
