I wonder, too, if rose’s Karmel cake from RHC would be a good match?
I wonder if some apple butter would emulsify into the completed frosting—or you could torte the 2 layers for 4 and put apple butter between 1&2 and 3&4, and the buttercream between 2 & 3 and then all around—and top with Julie’s poached—or even caramelized—apples and put walnuts all around the sides (is it safe to assume that all apple lovers also love walnuts?).
You can make Rose’s apple upside down cake—2 of them—and make them your two cake layers!!!!!!! I always wanted to do that with pineapple upside down cake. Make pineapple upside down cake, using carrot cake batter, and then sandwich the layers with cream cheese frosting and coat with coconut. Mmmmmm.