Magic Chocolate Cake

I've seen various recipes and flavours for this so-called 'magic cake' on several blogs and in a woman's magazine. I liked the idea of trying a chocolate one , but I can't honestly say where the original recipe comes from, as all the blogs I looked at referred back to a different blog! I think the original idea came from  this Spanish blog .

Why is it magic, well you have one very runny batter, and when it's cooked you have a 3 layer cake. The middle layer is really a chocolate custard. The mixture is so runny that I thought I'd forgotten an ingredient [it's like a pancake batter], but having checked the various recipes, I hadn't. It's the top and bottom layers that hold the middle custard together.
Well it's something different to try!

You need:

4 eggs at room temperature
150g caster sugar
1 tbspn water
125g butter
70g flour
45g cocoa
pinch salt
500ml full fat milk
few drops lemon juice

Preheat oven 160C/gas3
Grease a round 20/22 cm cake tin.
Melt the butter over simmering water or in a microwave and keep warm. Warm the milk.
Separate the eggs and beat the yolks, sugar and water for a few mins. Add the warm butter and carry on beating.
Sift the flour, cocoa and salt together and add to the batter, beating all the time.
Add the warm milk and beat well.
Wash and dry your beaters then whisk the egg whites and a few drops of lemon juice till firm. Add a spoonful to the batter and beat in, then fold in the rest carefully, a little at a time, using a spatula.
Spoon into the tin and bake for about 50 mins.
The middle will wobble [jiggle someone called it] a bit, and it will stay like this even when cold.
Leave the cake to cool before taking out of the tin. Sprinkle with some cocoa and keep in the fridge.

You can just about see 3 layers in the photo - the bottom layer is very thin, then you have the middle custard-type layer and a cakey top layer.
It's not too sweet and it melts in your mouth. One of the blogs said that the magic was when you bite into it - not sure if I agree with this, but it is a different sort of cake.
A few tips from people on the various blogs - if you use a stand mixer, beat the milk in by hand or the mixture splatters everywhere! The egg whites can look curdled when you've mixed them in, so just make sure that you've not left any big chunks.
Not an easy cake to get out of the tin - can crack easily.
One person just put all the mixture in a blender, but her cake looked like a custard tart, so maybe not a good idea!
If you're not put off by all these comments, it's an interesting cake to try. Oh, last thing, you need to keep it in the fridge!