Method

• Melt the butter with the olive oil in a large heavy-based saucepan.
• Add the onions and sprinkle in the sugar. Cook the onions, uncovered, over a low heat, stirring every so often to until the onions are soft and caramel in colour (this can take up to 1 hour).
• Add the wine, bring to the boil and reduce the wine by half. Add the Black Garlic Paste and beef stock. Simmer over a medium heat for 20 minutes. Season with salt and freshly ground black pepper to taste. Add the brandy if using.
• While the soup is simmering prepare the croûtes – preheat the oven to 240C/220Cfan/Gas 9. Brush both sides of the baguette slices with olive oil. Place them on a non-stick baking sheet. Put in the oven and cook for 7 minutes. Turn the toasts over, spread with mustard if using, sprinkle over the cheese and cook for a further 5 minutes until the cheese is bubbly and melted.

To Serve: ladle the soup into bowls. Place one cheese croûte on top of each soup bowl. Serve any remaining croûtes separately.

Top Tip: the success of this classic soup depends on the quality of the simple ingredients. BGK uses Pink Roscoff Onions for their gentle sweet flavour. Stock can vary in taste; if the soup needs an extra boost of flavour then add a beef stock pot.