Heat olive oil in a large pot over medium heat.
Add chopped onion and sauté until translucent.
Stir in sliced leeks and cook until soft.
Add diced potatoes and cook for a few minutes.
Pour in the broth and bring to a boil.
Reduce heat and simmer for 20 minutes until potatoes are tender.
Use an immersion blender to puree the soup until smooth.
Stir in heavy cream and season with salt and pepper.
Simmer for an additional 5 minutes to heat through.
Serve hot, garnished with fresh herbs.