Press Sauté and wait until the Instant Pot reads Hot.
Add butter and olive oil to the inner pot and stir until butter melts.
Add mushrooms, stir and cook for 2 minutes and add diced onion, minced garlic, dried thyme, and rosemary. Cook for about 4-5 minutes, stirring occasionally.
Add Arborio rice and stir until each grain is coated with the butter-oil mixture, cook rice for about 2 minutes.
Add white wine, stir to combine, and simmer for 2 minutes. Be careful as the rice will absorb the wine, stir frequently to notice when there is no more liquid, as the rice may burn.
Add chicken broth, stir well to combine.
Cover with the lid and lock it. Make sure the valve points to sealing. Select high pressure and set the timer for 6 minutes. The pressure will build for about 10 minutes.
Once the Instant Pot beeps and it's done cooking, carefully do a Quick Pressure Release by pointing the knob to Vent. Use a spatula or wooden spoon to move the knob, to avoid burning yourself with the steam.
Stir risotto well and season with salt and pepper to taste.
Stir in thawed green peas and Parmesan cheese (1/2 cup or 1 cup) until melted and fully combined.
If you have leftover risotto, either transfer it to a container, or remove the stainless steel pot from the Instant Pot, the risotto will continue to cook because of the residual heat.