Step 1

In a Dutch oven, heat the 1/4 cup olive oil over medium-low heat. Add the onions and stir to coat with the oil. Cook until the onions are fork-tender, about 15 minutes.

Step 2

Add the remaining 1 tablespoon olive oil and the butter and mix until the onion are well coated. Cook over medium-high heat for 20 more minutes.

Step 3

Add the salt and sugar, stirring frequently to prevent sticking, until the onions reach a nice brown hue, about an additional 15 minutes.

Step 4

Stir in the garlic and Marmite and cook, stirring, for 2 minutes, then immediately pour in the vermouth to deglaze the pan. Add the broth, bay leaves, thyme, and pepper, stirring gently. Cover the pot and cook for 30 minutes.

Step 5

Remove the bay leaves and add the brandy, if desired. Add more salt and/or pepper to taste.

Step 6

Preheat the oven to 400 °F.

Step 7

Place the bread on sheet pan and brush generously with olive oil. Bake until the bread is lightly toasted, about 5 minutes. Flip each piece over and cover each generously with the cheese. Leave the oven on but set the broiler to high.

Step 8

Ladle the soup and onions into six 2-cup broiler-proof bowls. Cut the cheese toasts in half and place a half on top of each bowl. Place the bowls on a baking sheet and set under the broiler until the cheese is melted, about 45 second. Remove from the oven. Be careful as the contents will extremely hot.

Step 9

Place each bowl on a small plate, add a sprinkle of Parmesan, and enjoy it while it's hot!