In a medium bowl, stir together the miniature marshmallows and pineapple chunks. Cover and chill in the refrigerator for at least 8 hours or overnight.

In a small saucepan, whisk together the reserved pineapple juice, sugar, beaten egg, vinegar, and flour. Cook over medium-low heat, stirring constantly until the mixture thickens.

Transfer the sauce to a bowl, cover, and chill for at least 8 hours or overnight. The next day, combine the chilled fruit mixture with the chilled sauce in a large serving bowl.

Carefully fold in the peanuts, Snickers, whipped topping, and chopped apples until well mixed, reserving some candy or nuts for garnish if you like. Cover and refrigerate until ready to serve. Before serving, drizzle with caramel sauce and add other toppings of your choice for garnish, if desired.