This custard is the ice cream base that my mentor Skye Gyngell taught me when I worked for her at Petersham Nurseries in London. I use it for all my ice creams and for unfrozen custard sauces. I’ve never used a different one, and I probably never will. Be sure not to whisk the egg yolks and sugar together until just before you’re ready to add the hot cream as the sugar can “cook” the yolk, making lumps.