There are a number of dishes that use a similar mixture of eggs and milk/cream to stand on it's own, or, with an extra filling; crème patissière, crème brûlée, quiche, flan, crème caramel...
Flans and quiches are also made as savory dishes, without the sugar of course, but, with an extra filling. I made a nice pumpkin flan not that long ago.
You can make a great number of variations on the egg + milk/cream mixture but a ratio of 1 whole egg to 100 ml of milk/cream will do the job, or, 2 eggyolk per 100 ml. The difference? The more cream and eggyolk, the fatter and the more silkier your result will be. The more milk and whole eggs, the more fluffy, somewhat grainier it will be. Also, the amount of eggs can change to make the structure more dense. A mixture of both eggs and eggyolks is best in many cases and certainly in KKV's creme caramel. You also need 20 gram sugar per 100 ml liquid.
It's not scientifical, but this is just what I would do if I were you, KKV.
- Be sure your mold is watertight. If not, wrap the whole outide in clingfilm. Also, pour some water in it to measure how much liquid it contains. Also, look for a lower cooking pot or tray in which the mold fits; you gonna need to fill the cooking pot or tray with HOT water, up to halfway the mold. And, also, you gonna need to butter or oil your mold thouroughly, or the filling will never get out.
- Warm the milk with a split vanillabean, marrow scraped out and put in the milk.
- Make the caramel; 100 gram sugar melted into lightbrown caramel, add 2 tbsp of water (carefully not to burn your hands!!) and a good squeeze of lemon juice. Let cool, then pour in the greased mold. You could leave the caramel out for now and pour it over the flan when it comes out of the oven. Your choice.
- Make the custard. Per 200 ml content of the mold; 1 egg + 2 eggyolks. If the mold holds -let's say- 500 ml, use 3 whole eggs and 4 yolks. That will be more than enough egg. I'm counting a little more eggyolk because it's not a small ramekin. More yolk will make it silkier.
Start by beating the eggs and yolks foamy with the sugar, then add the hot milk and whisk.
Put the mold in the cooking pot or tray, but first put a brandnew non-woven synthetic cleaningcloth dubblefolded on the bottom, this will prevent the custard from burning in the oven.
Pour the custard into the mold. Fill the cooking pot or tray halfway the height of the mold with hot water.
Oven 180°C, maybe 40-45 minutes.