Chocolate cake recipe for 9" tin please

[timetorefresh]

Been hunting internet for a good chocolate cake recipe for a 9" tin. Keep getting ones that measure in cups. I don't actually know how big a cup is. Does anyone please have a good recipe for a 9" tin? I'm hoping Mumsnet has the answer

Hummingbird Bakery - Mississippi Mud Cake. The best chocolate sponge cake you will ever make!
If you can't find it on the internet, let me know and I will upload a photo from my book (be warned it's covered in chocolate though as it's well used!)

A cup isn't a defined measurement, there are slight variations.

You could use any recipe and scale it accordingly.

So if it's for an 8 inch tin, just multiply everything by (4.5 x 4.5)/(4 x 4) because whatever you thought in school, you will one day need to know about calculating the area of a circle

Then just approximate with eggs, eg if you end up needing 3.5 eggs, just use 4 slightly smaller ones, or 3 large ones because, whatever Mary Berry and the like say, baking doesn't need to be exact. There are millions of slightly different recipes available and they all produce cake.

Thanks both

Nigella's Old Fashioned Chocolate Cake.

Been making them for years and wouldn't bother with another recipe. It's amazing.