Begin by making the homemade eggnog. Whisk the eggs and sugar together until light and fluffy. I learned the hard way that patience here is key; rushing can lead to a less smooth eggnog.

In a saucepan, gently heat the milk and heavy cream until warm but not boiling. Gradually temper the eggs by adding the warm milk mixture a little at a time, whisking constantly. This step is crucial to avoid scrambling the eggs, a mistake I made during my first attempt.

Return the mixture to the saucepan and cook over low heat, stirring constantly, until it thickens enough to coat the back of a spoon. This usually takes about 15 minutes. Remember, patience is key here.

Remove from heat and stir in the bourbon or rum if using, nutmeg, cinnamon, and vanilla extract. Allow the eggnog to cool, then refrigerate until chilled. I found that chilling it overnight enhances the flavors immensely.

When ready to make the eggnog latte, brew 2 shots of espresso. A strong coffee base is essential for the perfect balance of flavors.

Steam the milk until it's hot and frothy. I've learned that the ideal temperature is around 150°F (65°C) for that perfect froth without scalding the milk.

Mix the homemade eggnog with the steamed milk, adding sugar if desired. Gently stir to combine. The first time I did this, I was too vigorous and lost some of the frothiness. A gentle hand is best.

Pour the espresso into a large mug, followed by the eggnog and milk mixture. If you're feeling indulgent, top with a dollop of whipped heavy cream and a sprinkle of nutmeg for garnish.

Enjoy your homemade eggnog latte immediately, savoring each sip of this festive, cozy beverage.