Place trivet in pot, along with 5 cups of water. Turn on sauté setting and bring to a boil.
Add eggs to blender. Blend until fully broken up into a homogenous mixture, about 15 seconds. Add sugar and blend until fully incorporated. Finally, add milk, cream, vanilla, nutmeg, and salt. Blend for about 30 seconds, until all combined.
Pour eggnog into a large pyrex dish (1.75 quart). Place pyrex dish on top of trivet. Water should come up about halfway on the sides. Whisk eggnog frequently while water comes back up to a boil.
Once the eggnog reaches 150 degrees, switch Instant Pot to “keep warm” setting. Continue mixing frequently until the eggnog reaches 160 degrees. Then transfer to an airtight container and chill overnight.
If you prefer a boozy eggnog, add 1 cup of bourbon and mix well just before chilling overnight. DO NOT heat the alcohol up or it will lose all its goodness!