In a large soup pot, add olive oil, butter and garlic. Simmer until garlic is soft but not brown.
Add the rest of the ingredients (except for the broth and dry sherry) to the pot. Increase the heat to medium-high.
Mix all the ingredients together until well combined. Slowly cook until the onions are very soft and a deep caramel golden brown. Stir occasionally.
Deglaze the pot with dry the sherry. Then lower the heat and simmer for 10 minutes.
Add the beef broth or stock and cook on low for 2 hours.
Ladle soup into bowls.
Top with croutons and cover with provolone and parmesan cheeses.
Place bowls on a baking sheet and broil in oven until cheese has melted.
Mix the minced garlic and parsley together and garnish the soup with a small amount on top.