In a large pot, heat olive oil over medium heat. Add the chopped onions and sauté until translucent, about 5 minutes.

Add the sliced leeks and minced garlic, cooking for an additional 3-4 minutes until softened.

Stir in the diced potatoes and pour in the vegetable broth. Bring to a boil, then reduce heat and simmer for 20 minutes until the potatoes are tender.

Use an immersion blender to puree the soup until smooth, or transfer to a blender in batches.

If using, stir in the heavy cream and heat through. Season with salt and pepper to taste.

Ladle the soup into bowls and drizzle with olive oil and a sprinkle of fresh chives before serving.