Preheat oven to 180°C (160°C fan/Gas Mark 4).
Melt 25g of Jersey butter in a large saucepan over medium heat. Add the onion and garlic and cook until softened, about 5 minutes.
Add the Jersey Royal potatoes to the saucepan and cook for a further 2-3 minutes, stirring to coat them in the butter.
Pour in the vegetable broth and Jersey milk. Bring to a simmer, then reduce the heat and cook for 20-25 minutes, or until the potatoes are tender.
While the potatoes are cooking, prepare the croutons. In a bowl, toss the bread cubes with olive oil, remaining 25g of melted Jersey butter and Jersey Black Butter. Season with salt and pepper.
Spread the croutons on a baking sheet and bake in the preheated oven for 10-15 minutes, or until golden brown and crispy.
Once the potatoes are tender, remove the soup from the heat and stir in the watercress. Season with salt, pepper, and a pinch of nutmeg.
Using a blender (or an immersion blender), carefully blend the soup until smooth and creamy. Be careful when blending hot liquids.
Taste and adjust seasoning as needed.
Ladle the soup into bowls and garnish with the reserved watercress and crispy Black Butter croutons. Serve immediately.
Nutrition per serving (325g)
For a smoother soup, pass it through a fine-mesh sieve after blending.
If you don't have Jersey Black Butter, you can substitute with a small amount of molasses or a drizzle of balsamic glaze for a similar depth of flavor in the croutons.
The soup can be made ahead of time and reheated. Add a splash more milk when reheating if it becomes too thick.
This soup freezes well. Allow to cool completely before transferring to freezer-safe containers.
Oven
Stove
Blender (or immersion blender)
No wine pairing suggestions available for this recipe.