French Onion Soup

Begin by melting the butter together with the olive oil in a large heavy-based pan over medium heat. Add the thinly sliced onions and cover with a lid, allowing them to gently soften for about 10 minutes. This slow softening brings out the natural sweetness and prepares them for deeper caramelization. Sprinkle the onions with sugar, which helps speed up the caramelization process. Continue cooking uncovered for another 20 minutes, stirring frequently to prevent burning and to encourage even browning. You'll know the onions are ready when they take on a rich golden hue, emit an irresistible aroma, and feel tender enough to pinch easily between your fingers. In the final moments of cooking the onions, add the sliced garlic cloves to infuse the soup with a subtle garlicky note. Next, sprinkle in the plain flour and stir thoroughly to coat the onions, which will help thicken the soup later. Increase the heat to medium-high as you gradually pour in the dry white wine, stirring constantly to blend it smoothly. Follow by carefully stirring in the hot beef stock, then cover the pan and let the soup simmer gently for 15 to 20 minutes. This simmering melds the flavors together and transforms the mixture into a rich, comforting broth. While the soup simmers, prepare your toast slices. Turn on the grill to high to get ready for melting the cheese. To serve, ladle the steaming hot soup into heatproof bowls. Place one or two slices of toasted bread atop each bowl, then pile on the shredded Gruyère cheese generously. Pop the bowls under the grill until the cheese has fully melted and turned golden, forming a deliciously bubbly crust. Alternatively, you can grill the bread with the cheese separately and then serve it on top of the soup if you prefer a crispier, less soggy texture. Either way, serve immediately for the best experience with irresistibly gooey cheese and flavorful broth.