Preheat your oven to 350 degrees, place your bread slices on a baking sheet, brush olive oil across both sides of each slice, and bake for 7-10 minutes, or until golden brown

Slice the tops and bottoms of your onions off. Cut them in half, and slice them into thin strips

Heat a pan over medium to medium-high heat with some olive oil, Add your onions, sugar, and some salt and let everything cook until caramelized.

When your 45 minutes are up and your onions have transformed into a deep golden brown, add your beef broth

Bring the soup to a boil, reduce to a simmer, and cook for 15 minutes. Season to taste with salt and pepper

Turn your oven onto broil. Spoon the soup into oven safe bowls, and place the bowls on a baking sheet

Place 1-2 slices of bread on top of the soup, and top with shredded Gruyere cheese.

Place under the broiler for 1-3 minutes until the cheese is melted