Turn on a multi-functional pressure cooker (such as Instant Pot) and select Sauté function. Add butter and olive oil; stir until butter melts, about 2 minutes. Add mushrooms; cook, stirring occasionally, until slightly softened, about 3 minutes. Stir in onion; cook for 2 minutes. Add rosemary sprig; cook for 1 minute.
Stir rice into the Pot until each grain is coated with butter and olive oil mixture, about 2 minutes. Pour in wine; simmer for 3 minutes.
Pour in stock, stirring to scrape the sides of the Pot; simmer for 1 minute.
Close and lock the lid; turn the venting knob to sealing. Select high pressure according to manufacturer's instructions; set timer for 6 minutes. Allow 10 to 15 minutes for pressure to build.
Release pressure carefully using the quick-release method according to the manufacturer’s instructions, about 5 minutes. Unlock and remove the lid.
Stir risotto until creamy, about 1 minute. Discard rosemary sprig. Season with salt and black pepper; stir in Parmesan cheese until melted and combined.
Serve hot and enjoy!
