- In a large bowl, beat egg yolks until they become lighter in color. Beat in the sugar, whisking until fluffy.
- Combine the milk and cinnamon sticks, in a thick-bottomed saucepan. Slowly heat mixture on medium heat until it is steaming hot, but not boiling.
- Temper the eggs by slowly adding a small ladle full of the hot milk mixture into the eggs. Add a tablespoon first, mixing to combine, then stream in the rest while whisking constantly. Pour the egg mixture into the saucepan.
- Cook on medium heat (a very very gentle simmer), stirring constantly, until the eggnog begins to thicken slightly, and coats the back of the spoon. Do not allow the mixture to boil, or it will curdle. Remove the pot from the heat and stir in the cream. Let cool slightly in the fridge or freezer (you don’t want the alcohol to burn off)for about 30 minutes. Remove the cinnamon sticks, then mix in the vanilla, nutmeg, and the rum. Place back in the fridge and chill for 30 more minutes.
- Optional: Beat egg whites until they reach soft peaks. Add a teaspoon of sugar and continue to beat until they reach stiff peaks. Gently fold into eggnog.This creates a layer of foam on the top of your eggnog and makes it extra full-bodied.
- Garnish the eggnog with a cinnamon stick, and enjoy!