I have been delaying posting this recipe because I stole it from a friend, and didn't receive a reply when I asked if I could put it on here. But he's had plenty of time to say no, so I assume he means yes. :-) Logic, I likes it.
Despite its name, it's not really cake. It's a pie. And its delicious. Really delicious. Instead of using pastry for the base, however, you use a bread dough. This makes it a whole lot less greasy than it could be (greasiness is what puts me off quiche). Put aside quite a bit of time to let the dough rise properly, but if it doesn't, it's not a huge problem - I have had to give up when it had only increased in size by about 50% rather than 100%, and it is still delicious.
Mix all ingredients and place in a warm place until the dough has doubled in size. Meanwhile, make the filling.
750g onion, sliced into rings
20g cooking oil
60g bacon, diced (optional)
250g sour cream
1 tablespoon of caraway (optional)
Salt and pepper to taste
Melt butter with oil in a large frying pan or pot, and add onions (and bacon). Cook until transparent. Allow to cool slightly, then mix in sour cream, eggs, spices, and flour.
Roll out the dough to cover the bottom and sides of a 28-35cm spring form tin, pour in the filling, and bake in a preheated oven for ~ an hour at 200°C.