For French onion soup, peel onion and cut into fine rings. Cut bacon into fine cubes. Melt butter and sauté onion until brown. Fry bacon briefly. Dust with flour.
Add a dash of white wine and the beef broth (here 1 l water + 4 soup cubes). Let the soup simmer for about 1/2 hour so that it becomes creamy, but the onion does not completely boil away.
Cut circles from the toast so that they fit into the soup cup. Preheat oven to 300 °C grill. Divide soup into 4 soup bowls.
Place toast on top of soup and generously sprinkle grated cheese (Gouda, mountain cheese….) on top. Grill the soup for about 5-10 minutes so that the cheese is slightly crispy. Keep watching, it goes very quickly at the end.
Arrange the cups on plates. Caution. The cups and the soup are VERY HOT!!!!