On the stove (or in the microwave) heat eggnog and milk together, stirring frequently until it begins to steam (don't let it begin to boil). Remove from heat and use a whisk or immersion blender to whisk the milk until foamy.
Add hot coffee or espresso to your 12-ounce coffee cup. Pour eggnog mixture over the top. Taste, add sugar if you like a sweeter latte before adding optional toppings if desired.
Approximate nutritional information does not include optional whipped cream and was calculated using 2% milk.