Hit SAUTE on your 6 quart Instant Pot.
Once it reads HOT, melt butter and oil together.
Add in onions, brown sugar, salt, and pepper.
Cook, stirring regularly for 30 minutes. The Instant Pot may turn off, simply hit SAUTE again.
Stir in garlic in the last 30 seconds.
Deglaze with red wine, scraping any brown bits off the bottom to avoid a BURN notice, then hit CANCEL.
Stir in beef broth, Worcestershire, and bay leaves.
Cover and lock the lid - make sure the pressure valve is pointed towards SEALING.
Cook on HIGH pressure for 10 minutes.
Allow the Instant Pot to naturally release for 10 minutes, before flipping the valve to release any remaining pressure.
Remove the bay leaves, stir in balsamic vinegar, then taste and re-season, if necessary.
Place 4 oven safe bowls on a rimmed baking sheet, then fill each bowl evenly with the soup.
Top each bowl with the croutons, parmesan blend, provolone, then gruyere.*
Broil in the oven for 1-5 minutes, or until the cheese is bubbly and golden brown.
Serve immediately and enjoy!
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