Sprinkle chicken breasts with salt, pepper and Italian seasoning on both sides.
Press Saute on Instant Pot and wait until display says Hot. Add olive oil and saute chicken breasts on both sides until browned, in batches if necessary. Transfer chicken onto a plate, add chicken broth and deglaze the pot. Press Cancel.
Return seared chicken breasts to the Instant Pot, close the lid, set valve to Sealing and pressure cook chicken for 8 minutes. After wait 10 minutes and then release remaining pressure by turning pressure valve to Venting.
Remove chicken onto a plate and press Saute. In a small bowl, whisk milk and cornstarch, then pour into the Instant Pot and whisk. Add parmesan cheese, whisk again and let sauce cook for a few minutes until it thickens.
Slice chicken breasts against the grain, return to the pot and top with tomatoes and basil.
Serve hot over any pasta.
Notes
Store:Â Refrigerate in an airtight container for up to 5 days.
Freeze: Fully cook, cool completely and freeze in an airtight container for up to 3 months. Thaw in a fridge overnight.
Frozen chicken breasts: You can use frozen chicken breasts, just make sure they are separated and add 5 minutes to cook time. Also note that you won't be able to sear them which might result in a little bit less flavor but still good. Just add them seasoned on both sides to Instant Pot and cook.