Stashcook | Hearty Beef and Gruyère Onion Soup

Ingredients

• 960 ml beef broth
• 1 x 200 g block Gruyère cheese
• 4 slices French baguette
• 2 large yellow onions
• 1/4 tsp black pepper
• 2 tbsp butter, unsalted
• 1/2 tsp salt
• 1 tbsp balsamic vinegar
• 1/2 tsp dried thyme
• 1 bay leaf