French Onion Soup Gratinée

Cut the Brown onions in half root to tip, peel, and slice them thinly from root to tip, so each slice holds its shape. Pile them up, don't worry about crowding the board.

Cut the Baguette into 1.5 cm slices on the bias. Leave them on the board to dry while the soup cooks. Grate the Gruyère coarsely on the big holes.

⚠ Tip: Only day-old or lightly toasted bread works: fresh bread turns to paste under the cheese.

Put the Butter and Olive oil in a wide, heavy pot over medium heat. When the butter has melted and foams, tip in the onions and season with the Salt and the Sugar. Stir to coat. Cook, uncovered, stirring every few minutes, until the onions have collapsed and any liquid they give off has gone, about 20 min.

⚠ Tip: The salt draws the water out and the sugar is only there to help the onions brown: it is not there to make the soup sweet.

Lower the heat to medium heat and keep going, scraping the brown crust off the bottom of the pot with a wooden spoon every few minutes, until the onions are a deep, even mahogany and taste jammy, not sharp. Another 45 min to 1 h. This is the whole dish: if you rush it here and pull them gold, you will taste it in the bowl.

⚠ Tip: If the pot goes dry before the onions are dark, add a splash of water rather than more fat, and keep scraping.

Pour in the White wine and scrape the pot hard: everything stuck to the bottom is flavour. Let it bubble away until almost gone, about 2 min. Sprinkle over the Plain flour and stir for 1 min, until the raw flour smell is gone and the onions look coated and slightly dry.

Add the Beef stock, the Thyme and the Bay leaves and bring to a gentle bubble. Simmer, uncovered, for 30 min, skimming off any foam. The soup should coat a spoon and taste of roasted beef and sweet onion. Fish out the herbs, then stir in the Ground black pepper and, if you like, the Brandy.

⚠ Tip: Unsalted or weak stock will leave the soup thin and pale: reduce it a little longer if it doesn't taste beefy enough.

While the soup simmers, toast the bread until dry and crisp through. If you like, rub each slice once with the cut side of the Garlic.

⚠ Tip: A wet slice of bread will sink and turn the gratin into a mush, so dry it properly.

Heat the grill as hot as it will go. Ladle the soup into ovenproof bowls set on a tray: leave a good finger's width of space at the top. Float the toasted bread on the surface and heap the Gruyère over it in a thick, even blanket that reaches the rim, so it seals the bread down.

⚠ Tip: Cold bowls steal heat from the soup: warm them first, or the cheese will brown before the soup is hot.

Slide the bowls under the grill, close to the element, and gratinee for 5 min to 7 min, until the cheese is molten under the surface and blistered deep brown at the edges.

⚠ Tip: Watch it every second from the moment it browns: Gruyère goes from lacquered to bitter very fast.

Rest the bowls for 2 min so nobody burns their tongue, then take them to the table with a fork for the cheese and a spoon for the soup.