10 Medium yellow onions, peeled and sliced very thin
1/4 cup Olive oil
2 tsp Salt 
1 tsp Black pepper
2 Tbsp Butter, unsalted 
1 Ea. Garlic clove, minced.
2 tsp Sugar 
8 cups Beef stock
1ea Bay leaf
3ea Thyme, leaves removed and chopped
1 ea Baguette 
8 oz. Gruyere cheese, grated
 

In a large saucepan, warm the oil over medium-high heat. Add the onions, stirring constantly for 5 minutes. Add the salt and pepper, reduce to low and cook for 30 minutes, or until golden brown, stirring often. Add the butter, garlic and sugar and cook for 5 more minutes. Deglaze the pan with vermouth and cook until reduced by half. Add the stock, bay leaf and thyme and bring to a simmer. Reduce heat to medium and cook for 30 minutes.

Meanwhile, preheat the oven to 400°F. 

Slice the baguette into 12 diagonal slices. Place the slices on a parchment-lined baking sheet and divide the cheese over the sliced bread. Bake for 8-10 minutes or until melted and golden brown. 

After 30 minutes, add the brandy to the soup and cook for an additional 5 minutes. 

Ladle soup into bowls and top with cheesy croutons. Garnish with a sprig of thyme.