To complement the apple cake, serve this English custard.
1. Cut the vanilla pod in half and put the whole bean into the pot with the milk.
2. Bring the milk almost to a simmer. Remove from heat.
3. In a medium bowl, beat the yolks with the sugar until thick, light, and doubled in size.
4. Gradually pour the warm milk into the egg yolk and sugar mixture, whisking constantly.
5. Pour this back into the Saucy and cook on low heat for 15 to 20 minutes, stirring constantly with a flat-bottomed wooden spoon (it is essential not to let the custard boil — you are looking for a silky consistency).
6. The custard is ready when a finger drawn across the back of the wooden spoon leaves a light trail.
7. Remove from the heat and pour onto your apple cake.