Tonight I made a chocolate cake using my usual recipe :
240g Marge
240g Caster sugar
240 g Self Raising flour
4 eggs
A splash of milk
Enough cocoa to have a nice chocolate flavour.
Baked at 170 for about an hour.

I took it out of the oven and it was a nice height, but when it had cooled, it had shrunk to about half the height.
What did I do wrong ?

Perhaps it's because my plan was to bake the cake in one tin, measuring 8x4 and the splitting the cake in two.
I had another go this morning, baking the cake in two 8 inch sandwich tins. The cakes are still in the oven. This time I have added a teaspoon of baking powder and left out the milk.

Did you beat the eggs before adding them to the mixture? If so, how much? Manually or with machine?

Did you vary the temperature at all during cooking?

Where did you leave it to cool?

Do you have a fan-assisted oven?

Sorry for all the questions but perhaps the answer to one of these can help us solve the mystery! xx

p.s. Have you eaten the cake yet? Verdict?

I beat the eggs in one at a time with a hand-held electric mixer.
I did not vary the temperature or open the door during baking.
I left it in the cool kitchen to cool down.
Yes, I have a fan assisted oven.
I used it anyway, and I made Christmas themed cake
I made another cake this morning (see my addition to my original post - post #2) which I turned into a 'Gravity-defying' Mateser cake
I haven't eaten any cake yet, but the off cuts are very nice

It all sounds delicious!

I think perhaps the heat difference between the oven and the cooling place was perhaps too extreme for the air that had accumulated in this particular cake when it got hot. Regardless of how new or expensive an oven is, the temperatures is really a law unto itself and isn´t necessarily exactly what is shown on the knob / display. I don´t know where you live but maybe the cooling area was a bit cooler than usual.

Or it could just be these particular ingredients, with margerine, eggs and milk being natural products, every cake is going to be a bit different (sorry that sounds really patronising I have no doubt you appreciate that already!)

Possibly beat the eggs a bit less maybe just pop them in a cup and whisk quickly by hand.

Hope the final product tastes wonderful! xx

I have put pics of the finished cakes in the 'Your Home Made Cakes Pictures' thread

I checked it out - very impressed. Looks like the shrinking was not a problem in the end

Did you put it in a hot wash?