20cms square sponge recipe help please!

[bobkate]

So I tried converting from a round tin to square but major fail
I am wanting a deep square sponge cake, either to be baked as one or in two sessions ( I only have 1 x 20cms square cake tin!)
I tried googling and using a calculator to convert weights but it clearly failed as the cake sunk and didn't cook in the middle.
If anyone can give me a good sponge recipe that I can either cook as a whole cake then cut into 2 sandwich halves or to cook separately I would very much appreciate it. Thank you so much!

8" Square (20cm) has the same surface area as a 9" Round (23cm). Look for a 9" recipe. It is always easier to tweak the tin than the recipe as half an egg is a real faff.

Thanks...luckily a friend came to my aid with a recipe just in time!