Sauté the leeks: In a large pot, melt the butter over medium heat. Add the sliced leeks and cook for 6–8 minutes, stirring occasionally, until soft but not browned.

Add garlic and seasonings: Stir in the garlic, salt, and pepper. Cook for 1 minute until fragrant.

Simmer the soup: Add the potatoes, broth, and bay leaf. Bring to a simmer, then reduce the heat to low. Cover and cook for 15–20 minutes, or until the potatoes are tender.

Remove bay leaf and blend: Discard the bay leaf. Use an immersion blender to purée the soup until smooth (or blend in batches). For a chunkier texture, blend only half.

Add Parmesan and lemon: Stir in the grated Parmesan and lemon juice until smooth and melted. Add the cream or milk if using. Taste and add more salt, pepper or lemon juice as needed.

Serve: Ladle into bowls and top with chives or scallions and a twist of black pepper. Enjoy!