I used to be terrified of making custard. The idea of mixing hot liquid with eggs just sounds like a sure-fire way to end up with egg-drop soup. So, whenever I had to make custard, I would drizzle the hot liquid into the egg yolks ever so slowly, and I used a hand mixer to make sure every hot droplet was distributed into the eggs as quickly as possible. After a couple of successful custards, though, I started getting complacent. I ditched the hand mixer for a whisk and started pouring faster and faster, until...
Yesterday, I totally screwed up a batch of custard. We're talking big time egg-drop soup, pieces-of-coagulated-protein-floating-in-liquid style screwed up. This wake-up call reminded me that cooking is a science, and it requires due attention and care.
That said, I decided to write up some points that I've learned, so you won't make the same mistakes.
The typical custard recipe has the following steps:
1. Heat the liquid (milk, cream, etc) with sugar and flavoring (ex. vanilla) until boiling.
2. Add the hot liquid to beaten egg yolks
3. Cook the mixture over the stove top until "thickened to coat the back of the spoon".
Step #1 is fairly straight forward.
The goal for step #2 is to incorporate the hot liquid into the egg yolks in as gentle and gradual a way as possible, so no bit of egg yolk gets overcooked.
- Add some sugar to the egg yolks before tempering with hot milk/cream. I think it helps to add the sugar to the egg yolks to create some insulation, especially when the pot is heavy and it's easy to slop more than you intended into the eggs.