Combine orange peel, juice, and water in a 1-quart saucepan. Bring to boiling. Meanwhile, core pears from bottom end, leaving stems intact. Peel pears and set in saucepan stem end up. Simmer, covered, for 10 to 20 minutes or just until tender. Remove to individual serving dishes using a slotted spoon, placing them stem end up. Discard liquid from saucepan; add orange marmalade to saucepan and heat just until marmalade melts. Spoon over pears. Cover and chill 2 to 8 hours.
To serve, garnish each pear with a mint leaf, if desired. Makes 2 servings.