Rhubarb Kuchen (no-bake)

The inspiration for this dessert was the kuchen my Grandma made. Traditionally, the kuchen we knew (and I've seen other types of desserts and sweets called kuchen) was a layer of creamy, custardy filling on top of a pastry crust. I think it was made of cream, eggs, and sugar - that's my assumption. I had a bag of fresh-cut rhubarb in the fridge, and started to think about what kind of vegan analog I could come up with to recreate that kuchen taste. (to be cont.)