Stir together rice, butter, 1 cup evaporated milk, sugar, and salt in a medium saucepan, and cook, stirring often, over medium heat 20 minutes or until rice mixture is thick and creamy.
Place cherries in a small bowl; add boiling water to cover, and let stand 15 minutes.
Drain.
Stir together egg and remaining evaporated milk until blended; gradually pour into hot rice mixture in pan, stirring constantly. Cook, stirring often, 5 minutes.