Warm the oil and melt the butter in a large stockpot or Dutch oven over medium-low heat. Add the onions to the pot and cover, cook for 20-25 minutes, stirring occasionally. Add 3 of the thyme sprigs, and turn the pan lid slightly ajar. Place the pot into the preheated oven for 1 hour, stirring occasionally to ensure the onions aren’t sticking (this is the way to evenly caramelize the onions.)
Carefully take the pot from the oven and return it to the stovetop over medium heat. Stir the onions, scraping off all the brown bits from the sides of the pot. Slowly pour in the wine along with 1 teaspoon of the salt and cook for 5-8 minutes, so the liquid begins to reduce. Remove the stems of the first thyme sprigs, then add the rest of the thyme, beef broth, Worcestershire Sauce and reduce heat to low. Simmer for 40-50 minutes.
Cut the bread into rounds that will fit into the bowls or ramekins used for serving the soup, and toast the bread thoroughly on both sides in the oven or toaster.
When the soup is ready, ladle into bowls or ramekins. Place toasted bread on top of the soup and cover the bread with the grated cheese. Broil until cheese is melted and delicious.
Serve immediately and enjoy.
Make it Dairy Free: substitute olive oil for the butter, and do not top with cheese. Paleo-Friendly: use Dairy Free options and use coconut aminos in place of Worcestershire.