Bake the cake in a ceramic or glass baking dish as the cake will rise better.
Do not over mix the egg whites into the batter. You want to fold them in gently so they don't deflate.
You can use any type of milk, however the less fat content in the milk, means a less rich cake. I would stick to whole milk or 2% milk.
The rum adds a tiny bit of flavour to the cake. You can leave it out if you would like, and the cake will still taste amazing.
Store the cake in the the refrigerator. This cake tastes best served cold.