Make sure your cream cheese is at room temperature for easy mixing. For fast heating, remove the cream cheese from the package and cut into large chunks. Microwave in a medium bowl for 15 seconds.
In a medium bowl, whisk together the cream cheese, eggnog, powdered sugar, and vanilla. If you want the dip thinner, continue adding milk 1/2 Tablespoon at a time until you reach your desired consistency. Microwave again if needed as sometimes cold milk makes the cream cheese chunky again.
Add the cinnamon and ground nutmeg, and stir to combine. Season to taste with additional spices or sugar as needed.
Chill if desired and serve with your favorite dunkers like cookies.
If your dip is too thick, add a little milk. Chilling makes the dip thicker and as it warms, it will thin out again.