Melt the butter in a pot over low heat, being careful not to let it brown.

Add the sliced leek and onion to the pot. Sauté gently over low heat until the vegetables are soft and translucent, which is called 'sweating'.

Add the sliced potatoes to the pot and mix with the other vegetables.

Add water, granulated chicken bouillon, and white pepper to the pot.

Bring the soup to a boil, skim off any foam (lye), then reduce the heat to low, cover, and simmer for about 20 minutes until the vegetables are completely soft.

Turn off the heat. To cool the mixture down slightly, place the pot in a larger bowl filled with ice water.

Pour the cooled vegetable mixture into a blender and blend until it becomes a very smooth, fine-textured base.

Pour the blended soup into a bowl set over an ice bath to cool it down completely.

Once cooled, cover the soup base and chill it in the refrigerator for at least 3 hours.

After chilling, add the fresh cream and milk to the soup base to adjust the consistency. Whisk until well combined.

Season the soup with salt to taste. For an extra touch, add a little sherry if you like.

Ladle the finished Vichyssoise into a chilled bowl. Garnish with finely chopped chives and a drizzle of extra virgin olive oil.