6 large brown onions, peeled and sliced
2 apples, peeled, cored and sliced
2 teaspoons finely chopped rosemary
2 tablespoons olive oil
2 tablespoons butter
3 cloves garlic, crushed
2 teaspoons Dijon mustard
1 teaspoon Worcestershire sauce
1 tablespoon brown sugar
2 tablespoons plain flour
1 cup light ale
4 cups beef stock
sea salt and freshly ground pepper
slices sourdough bread, lightly toasted
150 grams grated Gruyère cheese
4 ovenproof soup bowls
Heat the oil and butter in a large saucepan and add the onions, apples and rosemary with a good pinch of salt. Cover and cook for 20 minutes, stirring occasionally and adding a splash of the ale if the onions start catching on the base of the pan. Uncover and cook for a further 15 minutes until a good golden colour. Stir in the garlic, mustard, Worcestershire sauce and the sugar then sprinkle over the flour and cook for 1 minute. Gradually add the remaining ale then the stock and season. Simmer for 20 minutes.
Preheat the grill to its highest setting.
To assemble: Place the bowls on a baking tray and ladle in the hot soup. Top with the bread then scatter over the cheese. Place under the grill and cook until the cheese is bubbling and golden.