This is an easy shavuos idea. Its easily customizable for most allergies. 

Bottom layer - any safe cookie, cupcake, or cake, crumbled 

Middle Layer - pudding. Can use instant pudding with pareve milk or you can make your own homade vanilla pudding

Top Layer - either shaved chocolate or more of the crumbs used in the bottom layer. 

You can make this version for the allergic family members and make the same thing with any no-bake cheesecake recipe for the rest of the family, so everyone can eat the same thing.