From http://blogs.phoenixnewtimes.com/bella/2013/11/aged-eggnog-recip...

Eggnog (based on Dr. Lancefield's recipe)
1 dozen eggs
2 cups sugar
1 quart half-and-half
1 750-ml bottle gold or dark rum
1 750-ml bottle bourbon
1 quart heavy cream
Nutmeg to taste (at least 1 teaspoon)

Beat eggs in a stand mixer until frothy and light. While mixer is running, gradually add sugar until fully dissolved. With mixer still running, add half-and-half, then slowly add bourbon and rum. Transfer mixture to a large bowl.

Whip heavy cream to soft peaks, and whisk into eggnog mixture. Add nutmeg and more sugar to taste.

Store covered in the refrigerator at least 3 weeks before serving.

"...aging has quite a positive effect on the nog. The significant amount of alcohol took the level of salmonella in the batch to zero after three weeks in the refrigerator. There's taste benefits, too; the flavors meld and improve after an extended stay in the refrigerator."

Serve in small glasses, garnished with a sprinkle of freshly grated nutmeg.

Caveat:

"While the risk of food-borne illness here is almost nonexistent, there's still a non-zero chance. It's a good idea to play it safe; If someone has a compromised immune system, they probably should pass on this eggnog. Also, keep an eye on it while it's mellowing; the alcohol should keep bacteria at bay (and indeed should sterilize the mixture given enough time), but if it starts to look or smell weird, pitch it and start again."