The hardest part about ice creams (and all custards, really) is not curdling the eggs. When egg yolks get too hot too quickly, the proteins bunch up into little tiny non-creamy chunks.
This is why some pumpkin pies get a little grainy and watery: the bunched-up proteins separate from the liquid that would normally be occupying the bunched-up space in creamy togetherness.
Top Tips to Prevent Curdling:
- Mix in a small amount of heated milk mixture into the egg yolk mixture to temper, or warm, it.
- Use a low, low temperature. Did I say low? I mean low.
- Stir. Try to use consistent, smooth strokes with a wooden spoon (whisks are good at keeping liquids moving -- and therefore cool -- but they also form bubbles. Custards do not like bubbles.)
- Cool the custard rapidly once it hits temperature. (This is why we have ice baths prepared.)
WARNING! I accidentally recorded with sound; turn off speakers for best results!
What Do You Do When Your Custard Curdles?
There isn't any way to get over the hurdle of a curdled custard. You can continue, and be satisfied with a non-perfectly-creamy ice cream, or you can start over.