In a saucepan, combine sugar, half and half and 2 cups of milk over medium heat. Whisk in cake mix powder. In a small bowl, whisk together cornstarch and 1/2 cup milk. Stir cornstarch mixture into into half and half mixture and bring to a boil.
Add food coloring if desired. Refrigerate for at least 1 hour or overnight. Process in an ice cream maker according to manufacturers directions. Pour into a freezer safe container and freeze for at least 2 hours.