Cut oranges crosswise in half. Squeeze juice from oranges, leaving shells intact. Reserve juice for another use. Place shells, cut sides up, in muffin pan cups.

Add ⅔ cup boiling water to each flavor gelatin mix in separate small bowl; stir 2 min. until completely dissolved. Spoon into orange shells. Refrigerate 3 hours or until firm.

Cut each orange half into 3 slices to serve.