Set your Instant Pot to sauté mode. Add unsalted butter and let it melt, then stir in the chopped onion and minced garlic. Sauté for 2-3 minutes until the onion is translucent and the garlic is fragrant.

Season the chicken breasts generously with salt and pepper. Add them to the pot and sear each breast for about 2-3 minutes until lightly golden.

Stir in the rinsed long-grain white rice for a few seconds until combined. Pour in the chicken broth and scrape the bottom of the pot to deglaze.

Secure the lid, set the pressure valve to sealing, and cook on high pressure for 10 minutes.

After cooking, perform a quick pressure release by moving the valve to venting. Stir in the heavy cream, frozen peas, and carrots.

Taste and adjust seasoning with additional salt and pepper if necessary. Mix thoroughly and serve hot.