In a large bowl, beat the cream cheese until creamy, about 1 minute. Beat in the sweetened condensed milk and vanilla until smooth and creamy. Beat in the chopped fruit cocktail, chopped maraschino cherries, chopped mandarin oranges, and drained pineapple until combined, about 20 seconds. Lastly, fold in the whipped topping until combined.
Spread the mixture into the prepared pie crust and smooth out the top. Refrigerate for at least 3 hours to set before serving.
Before serving, make your marshmallow whipped cream: In the bowl of a stand mixer, beat the heavy cream on high speed until soft peaks form. Add in the marshmallow creme and beat until stiff peaks form. Pipe the marshmallow whipped cream on top of the pie and garnish with additional fruit, nuts, marshmallows, if using. Store in the fridge.