In a large pot, heat the butter and olive oil over medium heat.

Add the chopped onion and garlic. Sauté for about 3-4 minutes until they become translucent.

Add the sliced leeks and diced potatoes. Cook for another 5 minutes, stirring occasionally.

Pour in the vegetable stock and bring the mixture to a boil. Reduce the heat, cover, and let it simmer for about 20-25 minutes or until the potatoes are tender.

Using an immersion blender, carefully blend the soup until smooth and creamy.

Return the soup to the stove and stir in the single cream. Heat it gently without boiling.

Season the soup with salt and black pepper according to your taste.

Serve hot, garnished with fresh chives.

Enjoy your delicious Potato Leek Soup!