Up until a few weeks ago this was a serious problem for me. Every cake I was cursed to come across ended up in this deformed state. I just couldn't understand how chefs got those perfectly level cakes. So I did my research and found out the reason for it was the outside of cakes cooking to fast.
To combat this I've come up with my pre-cake ritual. Now any one of these things could be stopping the cake deforming or it could be all of them together. But If I had to bet money, Id say number one was the key feature.
So. I turn my oven down about 30* less than what the recipe recommends. If it says cook at 180, cook at 150. This will increase the cooking time and nothing else, so keep pricking your cake with a skewer to check doneness. If I don't really have anything to do that day, I turn my oven all the way down to 100. This takes an age to cook the cake but it comes out beautifully flat and also risen very high.
2. Wrap Your Pan. Why? Most baking pans are thin and therefore get very hot around the edges, this cooks your cakes from the outside which isn't what we want. I make a band of tinfoil, as high as the pan and wrap it around the outside, like a ribbon around a cake. This should insulate the pan and make sure the cake doesn't cook too fast on the outside.
3. Smack Your Pan. Why? I'm not too sure about this one, but my grandmother swears it helps stop the cake rising in the centre. All I can think of is that by hitting the pan on the counter a few times, you even out the mixture and get rid of any high bits.
4. Dig A Hole. Why? Ok this appeals to my stupid side. If the cake rises in the centre then if there is less batter in the centre it should rise equally. So using my spoon I create an indent in the centre of the batter. I don't actually know if this helps but it makes me feel proactive.