The cake's three layers, which are "self-made".
The top of magic custard cake is a layer of fluffy cake. The bottom is a layer of starch which eats like kueh. What's in the middle? Smooth, milky custard.
My last recipe, pandan kaya cake, is a combination of cake and kueh. Magic custard cake gives you not only cake and kueh but custard as well. And you don't have to make the kueh and custard separately. Isn't that nice? It's how you have your cake, and eat kueh and custard too.
How to bake magic custard cake? Unfortunately, you can't wave a magic wand and make a neat stack of kueh, custard and cake fall out of the sky. You have to roll up your sleeves and make magic custard cake using the separated egg method.
The batter for magic custard cake is quite unusual. It has a humongous amount of milk, so it's extremely watery. If you put the watery batter in a pan with a loose bottom, it'll leak. You have to use a one-piece pan.
The thin batter, when it's baked at a low temperature, sets very slowly. That allows the ingredients to divide themselves into three layers:
1) The starch in the flour separates from the protein and, because it's dense, sinks to the bottom of the pan. There, it forms a layer that eats like kueh.
2) What happens to the protein in the flour? No longer weighed down by starch, it rises to the top of the pan, along with the very light egg whites in the batter. That's (kinda) how the cake layer is formed.
3) The egg yolks in the batter are sandwiched between the heaviest and lightest layer. The middle layer is my favourite. It's custard that's smooth, soft and milky.
As usual, follow my recipe if you want to bake the cake I bake. Don't be alarmed when your whisked egg whites become a bit grainy. That's the way it's supposed to be.
If the meringue isn't grainy at all, the cake layer will be too wet when the top is golden brown. Why? Because the water in creamy egg whites evaporates too slowly.
If the meringue is too grainy, the cake layer will be very thin because overly grainy egg whites are too inextensible to rise much. What's wrong with a thin cake layer? It doesn't absorb all of the fat in the batter, so there's a layer of butter between the custard and cake layer.
Mind you, it's not a good thing either if the cake layer rises a lot and becomes very thick. That's a sign it's going to be too wet.
When you hit the Goldilocks sweet spot, you'll get a fluffy cake layer that's neither too thick nor too thin, and neither too dry nor too wet. It goes very well with the custard and kueh, and the ratio of cake to custard and kueh is just right.
How do you make sure the meringue is grainy but not too grainy? By doing everything the recipe says, and not doing everything the recipe doesn't say.
You don't need a magic wand to bake magic custard cake. All you need is a good recipe.