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Why Is My Cake Rising in the Middle?
So, your cakes are rising too much in the middle. However, by using the following baking tips, you'll find that it's a fairly simple problem to correct.
The key to baking flat cakes is understanding what happens to the cake mixture when you bake a cake.
There are cakes that are more prone to rising due to the ingredients used, such as sponge cakes as they often contain a raising agent such as baking powder, and there are also cakes that don't rise naturally, such as brownies. The raising agent, such as baking powder, reacts with the wet ingredients (eggs, oil, butter) to produce bubbles of air which expand as the cake cooks, forming tiny holes in the mixture, and it is this which gives the much lighter result to sponge based cases as opposed to cakes without raising agents.
How to Bake Flat Cakes
If you've followed the recipe to the letter and your cake is rising too much in the middle, the first thing to try is turning down your oven.
The temperature within an oven does not always correspond exactly with the temperature on the dial. A 10 - 20C difference is not uncommon (my oven temperature is at least 10C hotter than the dial says).
This means that when you set it to 180C you may be cooking at 200C, which can make a lot of difference to a delicate sponge cake.
To start, make sure the cake mixture is evenly spread around the cake tin, any small lumps, bumps, and irregularities will be removed as the cake starts to cook. Make sure the cake is in the middle of the oven shelf - too close to one side or the other and the cake won't cook evenly.
Start by knocking 20C off the stated cooking temperature, i.e. if it says to cook a cake at 180C, cook it at 160C. It may need a couple of minutes longer but should rise much more evenly.
With bigger cakes (i.e. 10" in diameter and above) I find it useful to start the cake around 140C for 15mins to start an even rising process, then turn it up to 160C for the rest of the cooking time.
Each oven is different, so it may take a couple of attempts to find the right cooking temperature for your cake. Remember that it's better to start with a lower temperature and turn it up as an under-cooked cake can always be cooked longer, but once a cake has risen there is nothing you can do.
With a bit of practice, you should be able to bake a flat cake every time.
As the bubbles form the cake mixture cooks around them forming a sponge that holds it shape when cooled.
The 2 ingredients which best help a cake to rise ( apart from the raising agent itself) are flour and eggs.
Flour, of the wheat variety, contains gluten which has elastic-like properties that hold the cake together when cooked. Eggs act as a binding agent and trap air in the mixture which then expands as the cake is cooked causing the cake to rise.
The Root of the Problem
Cakes cook from the outside in, as the outside edges are closer to the heat source meaning the middle of the cake is the last part to cook through as the heat takes longer to reach that part of the cake.
The hotter the oven, the quicker the sides of the cake cook, and as they cook they form a crust meaning the cake can no longer rise at the edges. The problem is you are then left with a load of raising agent merrily doing its thing and reacting with heat and the wet cake ingredients to create bubbles of air and rise (and the only place it can go is the middle of the cake), hence cakes rising in the middle.
A slight rise is to be expected with any sponge-type cake but this should really be no more than a gentle curve of the edges rather than a dome effect in the middle.