Pour in 1/4 cup water or chicken broth into the inner pot of the Instant Pot.
Add the chicken breasts (fresh or frozen) in next.
Add the diced tomatoes, Italian seasoning, basil, salt, garlic and red pepper flakes into the instant pot. Do NOT stir.
Set the instant pot on high for 6 minutes for fresh chicken and 8 minutes for frozen. (NOTE: It will take about 10 minutes for the pressure to build up before the timer starts.)
NATURAL RELEASE. Allow the Instant Pot to release the pressure naturally, which means to DO NOTHING while the Instant Pot releases the pressure. Then carefully remove the lid.
To thicken the sauce, remove the chicken, press the SAUTE button, and allow it to cook down for an additional 5 to 10 minutes.
Spoon the thickened sauce over the chicken. Top with capers, mozzarella, parmesan, and/or burrata cheese balls (split open.) Serve over pasta.
Video
Notes
NOTE: Instant Pot recommends using at least 1/2 cup liquid when pressure cooking. I use 1/4 cup chicken broth because the canned diced tomatoes add liquid, and the chicken breasts will release chicken while they cook.It is also important to add the chicken broth first so this thin liquid is at the bottom of the Instant Pot to prevent a potential "burn message" from the Instant Pot. That can potentially happen if the tomatoes stick to the bottom of the pot. This is a very saucy sauce and can be left in the instant pot after the chicken is removed. It can be simmered for awhile until less saucy if you prefer. Serve this over noodles or rice and the sauce will be soaked up quickly. I like to use all three kinds of cheese, mozzarella, parmesan and burrata. The burrata gives a bit of creaminess to the dish. I used frozen chicken for this recipe and it cooks in the same amount of timeStorage: Store in an airtight container in the refrigerator for up to 5 days. This can be frozen for up to 3 months.