Wash potato peels thoroughly. Place in a large pot and cover with water. Bring to a boil and simmer for 15 minutes. Drain and rinse.

Heat olive oil in a large pot over medium heat. Add onion and cook until softened, about 5 minutes.

Add potato peels and vegetable broth to the pot. Bring to a boil, then reduce heat and simmer for 30 minutes, or until the peels are very tender.

Carefully transfer the soup to a blender (or use an immersion blender) and blend until smooth.

Return the soup to the pot. Stir in heavy cream (if using). Season with salt and pepper to taste.

Serve hot.