It's always nice to have the recipe before diagnosing baking problems; and nice to have a complete description of the problems as well. In this post, despite generations of ancestors wishing you to remain cae canny
, you may just have given enough information.
Your cake doesn't just collapse, it over-rises, then collapses, then sinks. The problem is not so much the collapse in the middle, but the early luft
and final sink-hole. Your cake has very little structure, because it uses very little flour. So, the way to control the rise and fall of dessert is in the mixing, baking and cooling stages. (What else is there?)
Okay, you've figured out that you're not supposed to overbeat after adding the flour. Well, don't overmix before either. You're creating air bubbles, and when the cake bakes, the air in the bubbles heats up, causing the bubbles to swell. When the cake cools down, the air shrinks; but there's not enough structure in the cake to support the swelling -- so it, as you say, collapses.
Don't use too hot a oven. Lower your temperature and bake longer -- you may even want to use a "bain-marie," as though baking a cheesecake. It will be similarly helpful to prevent the cake from cooling too fast. In fact, think of your cake as being like a sort of flan or custard rather than an actual cake -- just like a cheesecake. Which means:
- Don't overbeat during any part of the process.
- Use a moderate oven (about 300 or maybe even a little less).
- Use a bain-marie.
- Finally, allow the cake to cool in the oven -- first with the oven off and the door slightly open, then with the door open and the rack slid partly out (vestibule cooling) -- before putting it on a rack.
Hope this helps,
PS. Let us know what you try and how it works out.