Jersey Royal Potato and Onion Soup with Gruyère Croutons

Preheat oven to 180°C (350°F).

In a large pot or Dutch oven, melt butter with olive oil over medium heat. Add onions and garlic and cook until softened and translucent, about 8-10 minutes.

Add the chopped Jersey Royal potatoes to the pot and cook for another 5 minutes, stirring occasionally.

Pour in the vegetable broth, bring to a boil, then reduce heat and simmer for 20-25 minutes, or until the potatoes are very tender.

While the soup is simmering, prepare the croutons. Toss the sourdough bread cubes with a drizzle of olive oil, salt, and pepper. Spread them on a baking sheet and bake for 5 minutes, or until lightly toasted.

Remove the croutons from the oven and sprinkle generously with grated Gruyère cheese. Return to the oven and bake for another 2-3 minutes, or until the cheese is melted and golden brown.

Once the potatoes are tender, remove the soup from the heat. Using an immersion blender (or carefully transfer to a regular blender in batches), blend the soup until smooth and creamy.

Stir in the double cream (if using) and season with salt and pepper to taste.

Ladle the soup into bowls and top with the Gruyère croutons and fresh chives.