Top of cake lifts off. Any ideas?

I have a brilliant little book called 'The Awful Cook's Book' bought in 1965 for 3/6. It tells you what you've done wrong and how to remedy it!
It says: Cake sunk in centre - reasons:
1/Too much baking powder or other raising agent used.
2/Mixture was over-wet
3/Oven too cool
4/Oven door was opened and slammed shut
Remedy:
Let cake cool completely. Turn upside down and ice or decorate in the usual way. When once it's on a plate the sunken part will be out of sight and out of mind!

Thank you Chestnut I will have to try to eliminate these one by one. That book sounds great!

Another reason why a sponge will collapse is that the mixture is beaten too much and starting to curdle. It's a fine line between thoroughly beating and overdoing it.

A wee tip - turn it upside down.

I watched a You Tube clip once about cake strips. A padded foil strip, lined with something. You soak them in water before baking and wrap them around the edges of the tin. Stops the sides cooking more than the inside. Also keeps the top nice and flat.

www.youtube.com/watch?v=MNuAMoMgq70

Penygirl

Thank you Chestnut I will have to try to eliminate these one by one. That book sounds great!

This is the book (it's a booklet really but has LOADS of information) which may turn up on E-Bay or a rare book site I suppose.
Click image to enlarge.

I always use an all in one recipe. 150g of sr flour, 1 level tsp baking powder, 150g soft margarine straight from fridge and the same of caster sugar, 3 eggs.
Combine roughly, then whisk with electric mixer for just 45 seconds.
Bake in two lined sandwich tins for approx 25 mins at 160 Celsius fan oven.
I think you are maybe over mixing your mixture.

https://www.gransnet.com/uploads/talk/202106/medium-703048-img-20210619-wa0000.jpg https://www.gransnet.com/uploads/talk/202106/medium-901636-img-20210619-wa0001.jpg

Who just took a bite out of the side of the cake?
They say butter wouldn't melt! Grrrr!

Oh Ellianne!!

2 x irresistable!!
??

On Amazon 1968 version for £295 pounds - yes nearly £300 pounds - ? - no I haven’t missed a decimal point.

Ellianne what a lovely beautiful adorable dog. How could anyone not love such a cake stealing sweetie? Cake looks great. Hope you ate the rest.