The addition of roasted bone marrow enriches the soup and provides the base for the stock used in the recipe. Sliced baguette is best used for the cheesy toasts atop each bowl of soup. 

 Prep time: 40 mins /Cook time: 30 mins /Serves: 4-6

 Ingredients:

 500g brown onions, peeled and thinly sliced

–       2 cloves garlic, thinly sliced

–       50ml salted butter

–       6 sprigs fresh thyme

–       4 large beef marrow bones

–       2 beef stock cubes

–       Sea salt and black pepper

–       4 litres water

–       250ml dry red wine

–       1 baguette, sliced into rounds

–       200g grated Gruyère cheese

 Preheat the oven to 200°C. Line a baking sheet with foil or baking paper and arrange the marrow bones on it. Season the bones with salt and pepper and roast for 30 to 40 minutes or until browned and the marrow is easily removed. Remove the bone marrow and set aside.

 Meanwhile, fry the onions and garlic in the butter over very low heat until softened and jammy. Season with salt and pepper and the thyme leaves. Add the onions to a large soup pot along with the empty marrow bones. Pour over the water and crumble in the stock cube. Set the pot over medium heat and bring to a simmer. Cook for 15 minutes. Pour in the red wine and cook for a further 15 minutes. Remove the marrow bones and discard. Dish the soup into oven-proof dishes.

 For the toasts, spread each baguette slice with a little bone marrow and top with grated Gruyère. Balance two slices on the corner of each soup bowl and place the bowls beneath the grill for a few minutes or until the cheese is golden and bubbling.

Serve the soup immediately.