Set the instant pot on SAUTE function, let it heat up. Add olive oil (or butter + olive oil) once the butter melts add onion, carrots, and celery, cook until the veggies start to soften about 3-4 minutes.
Add garlic and sauté it for a few seconds.
Add chicken breasts, potatoes, mixed Italian seasoning, salt, and pepper; give a mix.
Next, add chicken broth. Mix and let it bubble for a few minutes.
Take the dough out of the fridge. Scoop one tablespoon of dumpling dough and place it on top of the broth.
Close the lid and pressure valve. Select the PRESSURE COOK button on HIGH PRESSURE and cook for 10 minutes.
Once the pressure-cooking cycle is over, allow the pressure to release naturally for 10 minutes. Then quick release the remaining pressure.
Open the lid and press the CANCEL button.
Carefully take the chicken and dumplings out with the help of tongs.
Shred the chicken breasts with a fork.
Make a slurry by mixing 1 tablespoon of cornstarch with 2 tablespoons of water.
Set the instant pot on SAUTE function.
Add the frozen peas and stir to combine.
Next, add the shredded chicken back to the INSTANT POT.
Once the liquid starts to bubble, add the cornstarch slurry and simmer until the broth has thickened.
CANCEL the SAUTE button.
Return the dumplings to the pot just before serving.