In a skillet over medium heat, cook diced bacon until browned and crispy, about 5–7 minutes. Add chopped onions and minced garlic, sautéing for an additional 3–4 minutes until the onions are translucent and fragrant.

Carefully pour the cooked bacon mixture into a 6-quart slow cooker, scraping any remaining bits from the skillet.

Layer the chicken breast on top of the bacon and onion mixture, followed by sliced russet potatoes, chopped carrots, and diced celery. Pour in the chicken broth, then sprinkle dried thyme, salt, and black pepper.

Cover the slow cooker and set it to low heat, cooking for 8–12 hours. Check for doneness around 7 hours.

Once cooked, remove the chicken and use an immersion blender to blend the soup until creamy. Return the shredded or chopped chicken and add fresh parsley.

Ladle soup into bowls and serve warm, optionally topping with low-fat cheese.