Place 2 tablespoons of butter in your Instant Pot and press saute. Once the butter has melted, add the onions and saute, stirring occasionally, for 5 minutes or until caramelized.
Add garlic cloves and chicken and saute for 2 minutes.
Add white wine and lemon juice to deglaze the pot, scraping any brown bits with a wooden spoon. Add rice and stir to combine.
Add the salt and stock. Stir.
Secure the lid with the steam vent in the sealed position. Press manual and set on high pressure for 6 minutes.
Once the timer sounds, press keep warm/cancel. Allow the Instant Pot to naturally pressure release for 10 minutes. Using an oven mitt, do a quick release. When the steam venting stops and the silver dial drops, carefully open the lid.
Add the remaining butter and the parmesan, parsley and lemon zest, then quickly stir until the butter and parmesan are fully mixed in. Allow the mixture to rest for 10 minutes.
Serve, garnished with shredded parmesan and chopped fresh flat-leaf parsley.