I have a normal sponge recipe i use for most cakes but when doing a large sheet cake or when I need a deep sponge I often find that the cake seems perectly cooked but when I cut it the middle section is still raw. I use a recipe of 100g each of sugar, flour & butter and usually make a very large batch of this. How can I make a deep sponge cake (so I only need two layers to sandwich together rather than 3 to get the right height to the cake) without it looking perfect but still being raw or being cooked well in the middle and dry and brown on the outside?! I'm very fond of my basic recipe as it always tastes fab and is moist so I don't want to have to change from it too much unless there's no alternative. Do I just need to lower the temp of teh oven and cook longer or will this make the cake dry out?

Any help would be appreciated!

I'd try using either a heating core (a glorified metal cup) or a couple of flower nails (greased, flat side down - my preferred method) in the center of your pan to help distribute the heat more evenly. Using Bake Even Strips will also help by keeping the temperature of the edges of the pan cooler (more even with the temperature of the center of your cake).
Hope this helps!

I agree with Justforfun751. That's the way I do it.

I'd keep your temperature down low, some people cook at 350, others go to 325. That will stop the outside getting too cooked before the inside is. You can try putting a flower nail in the middle to attract the heat (seems silly, but it works!), and you can try putting some tin foil loosely over the top once the outside seems cooked, that will stop it from burning while you wait for the inside.

This is the flower nail technique, a little less invasive than the heating core
http://cakecentral.com/articles/651/cake-baking-flower-nail-method-tutorial

[quote="zespri"]I'd keep your temperature down low, some people cook at 350, others go to 325. That will stop the outside getting too cooked before the inside is. You can try putting a flower nail in the middle to attract the heat (seems silly, but it works!), and you can try putting some tin foil loosely over the top once the outside seems cooked, that will stop it from burning while you wait for the inside.

This is exactly what I do when baking a bigger/deeper cake. Comes out great every time.