Combine boiling water and orange jello mix in a large bowl. Whisk to combine
Add in cold water and whisk together. Refrigerate for 10-15 minutes to chill.
Whisk in vanilla instant pudding mix until smooth. Refrigerate for 15-20 minutes until slightly thickened
Fold in Cool Whip, Mini marshmallows, and mandarin oranges until well distributed.
Refrigerate for at least an hour.
