How do the layers break down? Like which is which? Irish cream mix on top?
Yep, Irish cream/gelatin on top. I believe that Irish cream is made by mixing heavy cream, Irish whiskey and sugar together in some magical, non gross way, so it's delicious and and doesn't need a mixer for taste or color, and the alcohol content is low enough that it firms up fine.
what are the amounts needed for each of the ingredients?