01 - Heat olive oil in a large pot over medium heat. Add leeks, onion, celery, and garlic. Sauté for 6 to 8 minutes until softened but not browned.
02 - Add diced potatoes, thyme, bay leaf, salt, and pepper. Stir to combine.
03 - Pour in the chicken or vegetable broth. Bring to a boil, then reduce heat, cover, and simmer for 20 minutes or until potatoes are very tender.
04 - While the soup simmers, cook turkey bacon in a nonstick skillet over medium-high heat until crispy, about 5 to 7 minutes, turning as needed. Transfer to a paper towel-lined plate, then crumble or chop.
05 - Remove bay leaf from the soup. Using an immersion blender or working in batches with a countertop blender, purée the soup until smooth and creamy.
06 - Stir in milk or half-and-half and heavy cream. Gently reheat, but do not boil. Adjust seasoning with additional salt and pepper if needed.
07 - Ladle soup into bowls. Top each serving with crispy turkey bacon and a sprinkle of fresh chives or parsley.