Any clever cake bakers out there? How would I increase a recipe to make a bigger cake?

[Aranea]

I've got a Delia recipe for chocolate cake which is delicious but too small. It uses a 7" cake tin and last time it seemed only just enough for 7 people. I'd like to make it easily enough for 9.

But I'm intimidated by the chemistry of cake baking.... how can I do this? If I get a bigger tin and increase the quantities, how will I know how much to increase by?

Thanks...

Percentages. You needvto work out comparative volumes of tins, and then the percentage diff between them, and round up to the nearest egg! post the bigger tin size and i'll do it when i have a free hand...

well, if its only just enough big enough for 7, its really big enough for 6 so to feed 9 it wants to be 50% bigger. So if the recipe calls for 4 eggs you need 6 etc.

tin size... assuming you want the same depth then that would want an 8.5 diameter tin I think... so I guess its 8" a bit deeper or 9" a bit thinner.

The really tricky part is getting the cooking time right when you alter the size of a cake - I don't know if theres a good way to do that or if you'll just have to test it.

Thanks... Hmmm. I've just discovered that although the recipe calls for a 7" tin, I've been making it in one that measures 7 3/4 ".

So if I were to make it in a 9" tin, what do you think I should do with the quantities and cooking time?

Recipe calls for:
4oz self-raising flour
1 tsp baking powder
4oz marge
4oz sugar
2 eggs
2oz ground almonds
1tbsp cocoa powder mixed w/ water

Also does the depth of the tin matter?

I am frightened by cooking at the best of times, but cakes spook me completely

So 50% bigger is:

6oz self-raising flour
1.5 tsp baking powder
6oz marge
6oz sugar
3 eggs
3oz ground almonds
1.5 tbsp cocoa powder mixed w/ water

I think I'd do it for the normal time, test and then do 5 mins more, repeat till it seems done.

Agree with Grimma. Cakes just take practice, and for that you just need willing people to test your creations...

Depth of tin can affect cooking time, but the best thing to do is just keep an eye on it.

Thank you both. I will experiment in advance of dd1's birthday! Much appreciated.