Hit SAUTE on your 6 quart Instant Pot.
Once it reads HOT, add in olive oil, onion, celery, carrots, and garlic.
Cook, stirring regularly, for 5 minutes.
Hit CANCEL on the Instant Pot, then deglaze with wine. Be sure to scrape up any brown bits from the bottom to avoid a BURN reading.
Stir in the broth.
WITHOUT STIRRING, add in crushed tomatoes and tomato sauce, then sprinkle on basil, Italian seasoning, salt, pepper, red pepper flakes, and nutmeg.
Dollop tomato paste on top - again, do not stir, this helps avoid a BURN reading.
Cover and lock the lid; be sure the pressure valve is pointing toward SEALING.
Cook on HIGH pressure for 25 minutes.
Allow the Instant Pot to naturally release for 10 minutes, then flip the valve toward VENTING to release any remaining pressure.
Hit SAUTE on the Instant Pot.
In a small bowl, whisk together balsamic vinegar and cornstarch, then slowly whisk that mixture into the Instant Pot.
Simmer, stirring regularly, until the sauce has thickened to your liking.
Hit CANCEL on the Instant Pot, then stir in parmesan, brown sugar, and butter.
Taste and re-season, if necessary, then serve with cooked pasta and enjoy!
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