In a large pot, cook the bacon over medium heat until crispy. Remove and chop into small pieces. Set aside.
In the same pot, melt the butter. Add the onion and celery, and sauté until softened, about 3–4 minutes.
Stir in garlic and cook for 30 seconds until fragrant.
Sprinkle in the flour and cook for 1–2 minutes to form a roux.
Slowly whisk in the reserved clam juice and chicken broth until smooth.
Add the diced potatoes, bay leaves, and Italian seasoning. Bring to a boil, then reduce heat and simmer for 15 minutes, or until the potatoes are tender.
Season with salt and a pinch of cayenne pepper.
Stir in the milk, heavy cream, and clams. Simmer gently (do not boil) for 5 minutes until heated through.
Serve hot, garnished with crispy bacon and chopped parsley.