Dissolve the jello: In a large bowl, add the boiling water and the orange jello powder. Whisk thoroughly until the jello powder is completely dissolved.
Add cold water: Add the cold water to the bowl and stir to combine.
Chill the jello: Place the bowl in the refrigerator and chill for 20 minutes, or until the jello mixture has thickened slightly.
Add pudding mix: Add the instant vanilla cheesecake pudding mix to the thickened jello mixture. Whisk until the pudding mix is fully combined and the mixture is smooth.
Chill again: Return the bowl to the refrigerator and chill for another 20 minutes, or until the pudding mixture has thickened further.
Fold in Cool Whip, oranges, and marshmallows: To the thickened pudding mixture, add the Cool Whip, drained mandarin oranges, and miniature marshmallows. Gently fold the ingredients together until they are evenly distributed.
Chill the fluff: Cover the bowl with plastic wrap or a lid and refrigerate for 1 to 2 hours to allow the flavors to meld and the fluff to set.
Garnish (optional): Before serving, you can garnish the Creamsicle Orange Fluff with additional mandarin orange segments, miniature marshmallows, and a few mint leaves for a decorative touch.
Serve: Scoop the chilled Creamsicle Orange Fluff into serving dishes and enjoy!
