01 - Slice leeks lengthwise, rinse thoroughly to remove grit, then slice thinly.
02 - Melt butter in a large pot over medium heat; add onion, leeks, and garlic, sauté for 5 to 7 minutes until softened without browning.
03 - Incorporate diced potatoes, bay leaf, salt, and pepper; stir well to evenly coat the vegetables.
04 - Pour in vegetable stock, bring to a boil, then reduce heat and simmer covered for 20 minutes until potatoes are tender.
05 - Take out the bay leaf from the pot and discard.
06 - Use an immersion blender to purée the soup directly in the pot or blend in batches using a countertop blender, then return to pot.
07 - Stir in heavy cream and warm over low heat; adjust seasoning as needed.
08 - Ladle soup into bowls and garnish generously with finely chopped fresh chives.