01 - Slice leeks in half lengthwise, rinse thoroughly to remove grit, then slice thinly.
02 - Melt butter in a large pot over medium heat. Add diced onion, sliced leeks, and minced garlic. Sauté for 5 to 7 minutes until softened without browning.
03 - Stir in diced potatoes, bay leaf, kosher salt, and black pepper to coat evenly.
04 - Pour vegetable stock into the pot and bring to a boil. Reduce heat to maintain a simmer, cover, and cook for 20 minutes until potatoes are very tender.
05 - Discard the bay leaf from the pot.
06 - Use an immersion blender directly in the pot or blend in batches in a countertop blender until smooth, then return to the pot.
07 - Stir in heavy cream and warm gently over low heat. Adjust seasoning to taste.
08 - Ladle soup into bowls and garnish generously with finely chopped fresh chives.