I know there are some general tips on how to not have a dense/sunken cake, but I have a more specific problem. When I cook a simple sponge cake, with eggs beaten until ribbon stage, sugar and flour, it never fails and becomes very light and airy. When I make a butter cake (like a pound cake), it never fails either. But when I try to bake a butter sponge cake, my cake ALWAYS sinks in the middle! It’s not like it’s still gooey and undone, it just gets very dense in the bottom of the cake. I always beat my eggs until they are light yellow and airy. I can’t figure out what I am doing wrong, I used several recipes and they all fail, while all my normal sponge cake recipes succeed.
For example, I've used this recipe:
beat 6 eggs untill ribbon stage, adding 175 grams of sugar gradually. Sift in 150 grams of flour. Then add melted butter (room temp) and stir in carefully.
I've also used recipes where you have to beat butter with parts of the sugar, and then add the beaten egg mixture. Besides, I have baked at different oven temps for different amount of times.
Again, normal sponge cakes are no problem. So somehow, the butter ruins the cake, but I don't understand how! Please help?
It sounds like the butter is not being mixed thoroughly through the cake and is sinking to the bottom. An easy way to fix this is to place about a quarter of the mix in a separate small bowl (use a large baking spoon), pour the butter in and quickly but lightly mix the two together until the butter has disappeared and the cake mix looks very yellow. Pour this back over the top of the butter sponge mix, it should kind of float on top and using a large spatula or spoon gently fold through. Tips: make sure the butter is very warm to hot, if it isn't it won't mix through properly. Have everything ready to go as you need to work fast or you sponge will lose the air you have already beaten into it.
We call this process "lightening" the mix, not sure what other people might call it. This technique can also be used to fold pureed fruit through a sponge mix ie have fruit pureed ready to go, mix about 1/4 the sponge mix through and then fold back into the main sponge mix. It essentially helps you add a heavy liquid to a light sponge mix and mix it through thoroughly.