Prepare the leeks by trimming off the dark green parts. Thinly slice the white and pale green parts. Rinse them thoroughly under cold water to remove any dirt or grit.
Melt the butter in a 6-quart Dutch oven over medium-low heat. Add the leeks and salt. Cook until leeks have softened, stirring occasionally, about 20 minutes.
Add the white wine and deglaze the pot, scraping up any browned bits from the bottom. Allow the wine to cook down until slightly reduced, about 5 minutes.
Add the potatoes, bay leaves, thyme sprigs and chicken stock. Increase the temperature to medium-high, and bring to a boil. Then, reduce the heat to simmer, cover and cook until potatoes are soft and can be pierced with a fork, about 40 minutes.
While the soup is simmering, prepare the frizzled leeks. Heat the oil and butter in a small saucepan over medium-low heat to 225°F. Carefully pull the leek rings apart and add them to the pan. Stir occasionally to ensure even browning. When lightly browned, removed them with tongs or a slotted spoon and spread them out on paper towels to drain.
Once the soup has simmered and the potatoes are tender, turn off the heat and remove the bay leaves and thyme sprigs and discard. Using an immersion blender, carefully blend the soup until smooth and creamy. Be careful not to splatter hot soup out of the Dutch oven. Alternatively, you can transfer the soup in small batches to a regular blender and blend until smooth.
Stir in the heavy cream and season with salt and pepper. Adjust the seasoning as needed.
Ladle the creamy potato leek soup into bowls and garnish with a drizzle of white truffle oil, frizzled leeks and chopped chives. Serve alongside crusty bread for dipping and enjoy!