Press the Sauté key on the Instant Pot (it should say Normal, 30 mins). Add the butter and olive oil and wait until the butter melts.
Add the onion and cook, stirring for 5 minutes. Stir in the minced garlic and cook for 1 minute.
Add the rice and salt and stir well. Pour in the wine and stir until it has been absorbed, about 1 minute.
Stir in the butternut squash and sage and then add the broth.
Place and lock the lid, making sure the steam releasing handle is pointing to Sealing. Press Manual, High pressure and set to 6 minutes.
Release the pressure manually. Stir in half the blue cheese until it melts. Taste and adjust the seasoning if necessary. Serve garnished with extra blue cheese and the walnuts.
Notes
If you find the blue cheese is too strong, feel free to use grated Parmesan instead.