Begin by dicing the chicken breasts into bite-sized pieces and seasoning them lightly with salt and pepper.
Heat a skillet over medium heat, add a splash of oil, and sear the chicken pieces until they turn golden on the outside, about 3-4 minutes per batch. This step adds depth of flavor.
Transfer the seared chicken to the slow cooker, then add the diced carrots, chopped celery, and minced garlic on top.
Pour in the chicken broth, ensuring most ingredients are submerged, then sprinkle the dried thyme over everything.
Cover the slow cooker with the lid and set it to low. Let it cook gently for 6 to 8 hours until the chicken is tender and the vegetables are soft.
About 30 minutes before serving, cut the cream cheese into small chunks and stir them into the hot soup, allowing it to melt and create a rich, velvety broth.
Once the cream cheese is fully incorporated, taste the soup and adjust the seasoning with more salt, pepper, or herbs as desired.
Turn off the slow cooker and let the soup rest for a few minutes to thicken slightly and deepen the flavors.
Ladle the creamy chicken soup into bowls, garnish with fresh herbs or shredded cheese if you like, and serve hot for a comforting meal.