Adjusting cake recipe and cooking time

[lozlg]

Hi, i am making a chocolate cake for a friend. My recipe is split in two 7inch tins but I want to make it in two 9inch tins. I was wondering how to adjust the recipe as I will probably need more ingredients and how to adjust the cooking time? The 7 inch cake would take 35-40 mins on 180oc/gas 4. The recipe is below. Thanks.

My reciipe is:
115g plain chocolate
45ml milk
150g butter
150g muscovado sugar
3eggs
200g self raising flour
1tbs cocoa powder

[Sachs]

H loz, can't you just double up the recipe? Regards cake tin size, there's not much difference really, just fill cake tins as normal leaving enough depth for them to rise. You might have some cake mixture over to fill one half of another cake tin! Baking time, just use the same gas mark & check to see how baked they are. If they're not quite ready, leave on a little longer xxx

[dave123456]

The difference between a 7" and a 9" tin is about 1 to 1.68, or 5 to 3 if you like, so multiply all weights / volumes / quantities by 5 and divide by 3, and away you go.

[Sachs]

Think i chose the simplified method dave! I never did well in maths, very impressive!

[ailie]

Another way is to compare the volume of the 2 different sized tins (if you have them both). Fill one with water & tip it into the other, then you can mke a guesstimate about how much more mixture or less you will need for whichever tin (if you are scaling up or down). Or you can measure the water in a measuring jug & do some maths.
With your recipe, any scaling of ingredients will be in thirds to make it easy because of the eggs...so you go up to 4 eggs + an extra third of everything else or 5 eggs + 2/3 everything else.
Think that Dave & I make that the 5 egg mixture yum

[lozlg]

cool, thanks for your help everyone,