Marielle's French Onion Soup Recipe

Preheat an oven to 425 degrees F (220 degrees C).

Heat the butter in a skillet over medium heat. Stir in the onion; cook and stir until the onion has softened and turned translucent about 5 minutes. Reduce heat to medium-low and continue cooking and stirring until the onion is very tender and dark brown 15 to 20 minutes more. Stir in the flour; cook and stir for a few minutes then gradually add the beef broth and water. Bring to a boil then simmer for 20 minutes.

Arrange French bread slices on a baking sheet and sprinkle with Parmesan and Swiss cheese.

Bake in the preheated oven until the cheese is lightly browned and melted about 10 minutes. Divide the soup into 6 bowls and top with the cheesy bread.