Spray four silicone muffin cups with cooking spray and set aside.
In a small bowl, whisk together the eggs, milk, salt, and pepper.
Evenly distribute the egg mixture into the four muffin cups.
Evenly divide sausage and drop into the egg mixture.
Top each with 1/2 tablespoon cheddar cheese.
Pour water into the Instant Pot.
Place a trivet in the Instant Pot.
Place the filled muffin cups inside of a (7-inch) cake pan. Top the pan with a paper towel and a piece of foil crimped around the edges of the pan.
Make a foil sling and carefully lower the cake pan down onto the trivet.
Close the lid and set the pressure release to sealing.
Press the Manual or Pressure Cook button and adjust cook time to 5 minutes.
Let the pressure release naturally for 2 minutes and then quick release the remaining pressure.
Remove the foil from the top of the muffin cups and than carefully remove the egg muffins.
Enjoy immediately and refrigerate any leftovers.