Turn the instant pot to saute mode. Add the olive oil and butter. Allow to melt and coat the bottom of the instant pot.
Toss in the carrots, celery, and onion. Saute for 5 minutes.
Add the chicken breast and seasonings. Give a quick stir.
Rinse the rice in a mesh colander under cold water. Drain and add to the instant pot. Stir for 1 minute to allow any excess fat to be absorbed by the rice.
Pour in the chicken stock and stir.
Cover and set to manual pressure on High for 5 minutes. Allow to naturally release for 5 more minutes. Quick release the rest of the pressure.
Add the frozen peas on top and stir.
Serve garnished with fresh parsley.
You can store your leftover chicken and rice in an air-tight container kept in the refrigerator for 3 days. If you'd like to freeze it, store it in an air-tight container or freezer bag for up to 3 months. Add a splash of water before reheating to regain some moisture.