Open the can of chicken and put it in the bottom of the pot. Use the spoon to break up the meat into smaller pieces.
Add the pasta to the pot, then pour the can of chicken broth and water over the pasta. Add the teaspoon of salt, if desired. Remember that the canned chicken broth has some salt, so you decide how salty you like it.
Set the lid and close the valve on the InstaPot. Set it to manual pressure or high for a two-minute cooking cycle. When the time's up, let the pasta manually release the steam for five minutes. After five minutes, you may release any remaining steam.
Stir the pasta. You don't need to drain it.
Put the cubed Velveeta and milk into the pot, stir it into the pasta. Replace the lid on the Instant pot and let it sit for three minutes. The heat of the pasta will melt the cheese.
Give the pasta one last stir. It will be very creamy and "loose" in texture. If you prefer a thicker cheese sauce, skip the milk! Also, know that it will thicken as the cheese cools. Dust with paprika and black pepper, to taste.