Heat a large dutch oven or pot to medium heat and add olive oil, onion and ½ teaspoon salt.
Cook for 5 minutes, stirring frequently, then reduce heat to medium low. Cook for 45-60 more minutes until onions are caramelized. Stir frequently to keep them from sticking to the bottom of the pot.
Add garlic and thyme and let cook for 1 minute, then add wine and sherry vinegar to deglaze and scrape bottom of the pot.
Stir in the flour for 1 minute.
To the pot stir in broth, Worcestershire sauce, salt, pepper and pasta. Bring to a boil.
Cover, reduce heat to simmer and let cook for 15-20 minutes, until the liquid is absorbed and pasta is cooked to al dente.
Turn off heat and stir in heavy cream and cheese.
Serve topped with a sprinkle of parmesan and fresh parsley.
