"I love this recipe. It has become a tradition here in the winter.
Some of the reviewers complained of lumps. To avoid that, when ladling in the cream and milk, do so slowly while mixing constantly. Also do the same when after mixing in the eggs to the milk and cream. This is to help warm it up slowly and the stiring will help keep you from getting scrambled eggs instead of egg nog. Eggs cook very quickly if your not careful. I can now do it without any lumps but have messed it up a couple times when I was in too much of a hurry to combine the two.
It is a bit more work than some but well worth it.