Pour 5 cups of water into your instant pot. Turn on sauté mode. While you make your eggnog, your instant pot will have the opportunity to heat up. Place the trivet inside your Instant pot.
In a large blender, blend your eggs for about 30 seconds.
Add in your sugar to the blender. Blend well until fully incorporated for about 30 seconds.
Add in the rest of your ingredients: whole milk, heavy cream, vanilla extract, nutmeg, and salt.
Once all of the ingredients have been fully blended, pour into a large bowl that will fit inside your instant pot. Make sure to measure your bowl for the instant pot prior to pouring your eggnog mixture in.
Place your bowl inside of your instant pot on the trivet.
Pour the eggnog mixture into your bowl.
As your eggnog starts to warm, make sure that you whisk often.
Continue this process until your eggnog mixture reaches 155°. At 155°, press cancel on your instant pot, and select the warm setting. Continue to whisk on the warm setting until your eggnog reaches 160°. As soon as your eggnog reaches 160°, press cancel on your instant pot. Using a ladle, scoop out the instant pot mixture to a container that can be sealed (such as a bowl with a lid, or a mason jar).
Let the eggnog sit on the counter until it reaches room temperature. Once it has reached room temperature, place in the fridge until it is cooled.
Once completely cooled, pour into your favorite glass, top with whip cream, or nutmeg, or both!