Season the cubed chicken with salt, pepper, paprika, and garlic powder.
In the instant pot, add the chopped onions in an even layer. Then, add the cubed chicken in an even layer. Do not stir.
Add the egg noodles on top of the chicken in an even layer. Do not stir.
Pour the broth over the top and top off with the sliced mushrooms. Do not stir.
Pressure cook for 3 minutes and natural pressure release for 10 minutes before quick releasing.
Add the Dijon mustard, Worcestershire, cream cheese, and sour cream to the Instant Pot and stir until everything is well combined. Garnish with parsley. Serve immediately.