Melon Cream. It's good off the shake too!
Bavarian Cream/Vienna Cream
Vienna Cream gives that light cream with a subtle vanilla, Bavarian Cream thickens it up and provides that thick dairy mouth-feel
Custard Pi 3.14
This is used to thicken everything up nicely, it also adds to the vanilla slightly, and eats any of the harshness that the Lemon provides.
Tartness. It prevents the combination of creams from getting too heavy and thick through tartness
This provides the main flavour note, underpinned by Double Apple.