1. Heat butter in a pan.
2. Fry the onions till they become golden brown while stirring continuously.
3. Add flour while stirring and cook for 2 minutes.
4. Add the stock and bring to a boil.
5. Add salt, bay leaves and black pepper powder and simmer for half an hour.
6. Remove the bay leaves.
7. Cut the bread slices into half and cover with the grated cheese and grill until the cheese melts.
8. Serve the soup in a bowl with the bread slice floating.

For veg stock:
Cook chopped onion, carrots, garlic and celery in a pressure cooker. Once done, turn off the gas. Strain using a strainer. Use the liquid for making soup.