In a large pot or Dutch oven, melt the butter with the olive oil over medium heat. Add the sliced onions and cook, stirring occasionally, until the onions are caramelized and golden brown, about 25-30 minutes.

Stir in the minced garlic, sugar, salt, and black pepper. Cook for an additional 2-3 minutes until the garlic is fragrant.

Pour in the broth, water, white wine (if using), Worcestershire sauce, thyme, and bay leaf. Bring the soup to a simmer and let it cook for 15-20 minutes to allow the flavors to meld together.

While the soup is simmering, cook the gnocchi separately according to the package instructions. Drain and set aside.

Preheat the oven's broiler.

Once the soup has simmered, remove the bay leaf. Ladle the soup into oven-safe bowls or ramekins. Place a handful of cooked gnocchi on top of each bowl of soup.

Sprinkle a generous amount of shredded Gruyere or Swiss cheese over the gnocchi and soup in each bowl.

Place the bowls on a baking sheet and broil for 2-3 minutes, or until the cheese is bubbly and golden brown.

Carefully remove from the oven (the bowls will be hot!) and garnish with chopped fresh parsley.

Allow the soup to cool slightly before serving to avoid burning your mouth. Enjoy this comforting French Onion Gnocchi Soup!