substitution of whipping cream for water in jello
There are a variety of recipes on the web for making creamy jello.

There seem to be a few options including:


Method 1 - Using the quick-set method, add 8 oz of defrosted whipped cream topping (cool whip) after icing the Jell-o.
Method 2 - Using the regular or quick set method, replace some of the cold or cool water with cream
Method 3 - Using the regular or quick set method, replace some of the cold or cool water with melted ice cream 


The links take you to examples of recipes with more in-depth discussion of the specifics but there are many others out there.