un-eggnog, anyone?

My family celebrates christmas with "float." No, not root beer and ice cream, but a cousin of eggnog. The recipe calls for milk, beaten egg whites and sugar cooked until just boiling. You drink it cold and it is rich and airy at the same time.
My mother has passed and my sisters and I don't know where she got the recipe. I do know that she made it every year without having the recipe written down anywhere.
Has anyone ever had this? Is it called by another name? The internet has been no help in solving this mystery so far.
thanks!

Sounds like a simple recipe for boiled custard to me. Very similar to eggnog, yes. As a kid I actually preferred it to eggnog, which was a little too distinctly flavored for me at the time.