Drain pineapple, reserving juice.
In large bowl, stir together pineapple chunks and marshmallows; cover and chill for up to 24 hours.
For dressing, in a small saucepan stir together the sugar, flour, reserved pineapple juice, vinegar, and egg.
Cook and stir over medium heat, just until mixture bubbles.
Reduce heat; cook and stir for 2 minutes more.
Transfer the mixture to a small bowl.
Cover and chill.
To serve, add chilled dressing and apples, cool whip, cherries, and peanuts to marshmallow mixture; stir to mix well.