Top with GruyereSwiss, or your favorite cheese to melt on top.
Slice onions into very thin slices.
Use a large stockpot over medium to high heat. Add the butter and oil to the pan until it’s melted.
Add the sliced onions to the hot pan and mix until the onions are fully coated.
Cook the onions until they start to brown slightly and caramelize. This may take 15 to 20 minutes.
Add the 1/4 cup of dry white wine or apple cider vinegar and scrape the brown color at the bottom of the pan while stirring long enough for most of the liquid to evaporate. This is known as deglazing the pan and it releases the brown bits that are full of flavor into the onions. This will only take a couple of minutes.
Add the beef broth, thyme, Worcestershire sauce, salt, and pepper.
Taste and add more salt and pepper if needed.
Make the toasted bread topping:
Toast the bread.
In a small bowl, combine the butter and garlic powder.
Spread the butter mixture over the toasted bread.
Cut the bread into cubes.
Putting it all together!
Preheat the oven to 350 degrees.
Divide the soup into individual servings using oven-safe soup bowls.
Top each serving with a small amount of toasted bread cubs and shredded cheese.
Place the oven-safe soup bowls on a large baking sheet.
Using the middle rack, place the baking sheet in the oven for about 5 minutes or just love enough for the cheese to melt completely.
Switch the oven to broil and allow the cheese to brown slightly on the top. This will only take a couple of minutes until the cheese has browned and is bubbly.
Remove the soup from the oven and allow it to cool slightly before serving it.