Leek, Onion, and Potato Soup

1. **Prepare the Leeks:** Trim the leeks by removing the root ends and tough green tops. Halve the white and light green parts lengthwise, then slice them thinly. Rinse thoroughly under cold water to remove any grit.

2. **Sauté the Vegetables:** In a large saucepan, melt the butter over medium heat. Add the sliced leeks and chopped onion. Cook, stirring occasionally, until they begin to soften, about 5 minutes.

3. **Add Potatoes:** Incorporate the diced potatoes into the saucepan, stirring to combine with the leeks and onions.

4. **Season:** Sprinkle in the salt and black pepper, mixing well to ensure even seasoning.

5. **Add Broth and Milk:** Pour in the vegetable broth and whole milk. Stir to combine all ingredients.

6. **Simmer:** Bring the mixture to a gentle boil, then reduce the heat to low. Cover and let it simmer for 20-25 minutes, or until the potatoes are tender.

7. **Blend the Soup:** Using an immersion blender, purée the soup until smooth. If you don't have an immersion blender, carefully transfer the soup in batches to a regular blender and purée until smooth.

8. **Adjust Seasoning:** Taste the soup and adjust the seasoning with additional salt and pepper if needed.

9. **Serve:** Ladle the soup into bowls and garnish with freshly chopped chives.

10. **Optional:** For a richer flavor, swirl in a tablespoon of heavy cream before serving.