It says to add 1/3 of the hot mix into the egg then all of it goes in the saucepan. This is done to prevent the egg from cookin to quickly and creating lumps. Basically you are making a custard.
This recipe is confusing. It says to add 1/3 of the hot half and half mixture. What about the other two thirds or is it 1/3 at a time. I wish there was pictures. It seems odd to waste two thirds of the mixture. Will try it but I hope someone is able to clarify this recipe better!