- 1.5kg/3lb 5oz brown onions, sliced
- 85g/3oz unsalted butter
- 1 tbsp olive oil
- 1 tsp thyme leaves
- 2 bay leaves
- 1 tsp salt
- 2 tsp caster sugar
- 25g/10z plain flour
- 1 bottle dry white wine
- 2 litres/3 pints 10½fl oz chicken or vegetable stock
- 175g/6oz gruyère cheese, grated
- 12 x 2cm/¾in slices of French bread, toasted on both sides
- 1 garlic clove
- 3 egg yolks
- 150ml/¼ pint double cream
- 2 tbsp of brandy
- 4 tbsp of madeira
- Preheat the oven to 190C/375F/Gas 5.
- Place the onion, butter, oil, thyme, bay leaves, salt and sugar in a heavy-based saucepan and cook over a medium heat for 40 minutes, stirring from time to time. The onions should be golden and soft.
- Stir in the flour and cook over a low heat for a further 10 minutes.
- Pour in the wine, stir to combine, and cook for 10 minutes.
- Add the stock and cook over a medium heat for a further 20 minutes. The soup can be prepared up to 48 hours ahead up to this point.
- Scatter a little cheese (don't use it all) over the bottom of a large oven-proof tureen or 6-8 oven-proof soup bowls placed on a baking sheet.
- Pour in the soup. Rub the toast slices with the garlic clove and float on the top of soup.
- Top with the remaining cheese and place in the oven until bubbling and golden brown, about 20 minutes from hot or 40 minutes from cold.
- Beat together the egg yolks, cream, brandy and Madeira. When the soup is ready to serve, lift the cheesy crust and pour cream mixture into the soup, or serve in a jug and offer separately to your guests.