Add the liner to your Instant Pot and press the 'saute' button. Once hot add the oil.
2 tbsp extra virgin olive oil
Add the chicken pieces and cook, stirring often, until they're golden brown on the outside but not cooked through.
1 lb boneless, skinless chicken breasts
Add the onion and garlic to the pot and cook for 2-3 minutes, stirring often, until softened.
1 yellow onion, 4 cloves garlic
Pour 1 cup of broth into the pot and use a sturdy wooden spoon to deglaze the bottom of the pot, loosening up any stuck on browned bits. Hit the 'cancel' button.
3 cups chicken broth
Add the pasta to the pot, followed by the rest of the broth. Pour the tomato sauce evenly out overtop of the broth, but DO NOT stir.
12 oz dry pasta, 1 15 oz can tomato sauce
Add the lid to the pot turning to close, set the vent valve to the sealed position, and pressure cook on HIGH for 5 minutes.
Carefully open the vent valve, but avoid the hot steam escaping for a quick release. Add the mozzarella cheese and stir everything together until evenly combined.
1 cup shredded mozzarella cheese
Sprinkle the remaining cheese evenly out overtop and let sit for a couple minutes until melted.
1/2 cup shredded Parmesan cheese
Serve and enjoy!