Set the Instant Pot to SAUTE and add 2 tablespoons of olive oil.
When the oil gets hot add the chicken breast and cook until browned on all sides, approximately 5-7 minutes. Remove from the pot and set aside.
Add the onions, celery, and garlic. Cook for approximately 5 minutes, or until the onions soften and turn translucent. Make sure to use your spoon to scrape up the browned bits from the bottom of the pan as the vegetables cook.
Add the broccoli and then the salt to the vegetables and stir together.
Pour in the chicken broth. If there are any browned bits left on the bottom of the pan use the liquid to help you scrape them up.
Press CANCEL to end the saute mode.
Add the chicken back to the pot and stir in.
Add the rice on top. Do NOT stir the rice in but do press it down gently to make sure it is all in the liquid.
Lock the lid in place and turn the valve to SEALING. Set to HIGH pressure for 5 minutes.
When the timer goes off press CANCEL and let the pot do a natural release for 5 minutes.
After a 5 minute natural release carefully flip the valve to VENTING and let the remaining steam escape.
When the pin drops down the lid is safe to open. Remove the lid and stir everything together.
Add the cheddar cheese and place the lid back on top of the pot letting it all sit for approximately 5 minutes to let the cheese melt.
Stir together again and serve.