Press the sauté button on the Instant Pot. Add and melt the butter. Add the onion and stir fry for 3-5 minutes until onions are translucent. Add garlic and rice and cook for an additional minute. Add ½ cup broth and stir for 2-3 minutes until it is absorbed by the rice.
Add the remaining 1 ½ cups broth, parmesan cheese, salt and pepper. Lock lid.
Press Pressure Cook and adjust time to 10 minutes. When timer beeps, let pressure release naturally for 10 minutes. Quick release any additional pressure until float valve drops and then unlock lid.