ADD boiling water to gelatin mixes in large bowl; stir 2 min. until completely dissolved. Place 1 cake cube in each of 24 mini muffin cups lined with foil liners; cover with gelatin. Refrigerate 2 hours or until firm.
BEAT Neufchatel in small bowl with mixer until creamy. Gradually beat in sugar. Gently stir in COOL WHIP and zest.
SPOON into pastry bag fitted with star tip. Use to pipe Neufchatel mixture over trifles.