Start by heating olive oil in a skillet over medium heat. Add the chopped onion, minced garlic, and diced root vegetables, sautéing until the vegetables are lightly browned and the onion is translucent, about 5-7 minutes. This layering of flavors sets a fragrant base for the stew.
While the vegetables cook, season the chicken thighs with salt, pepper, and dried thyme. Pat them dry to help them brown properly.
Place the seasoned chicken thighs into the skillet and sear for about 3-4 minutes per side, until they develop a nice golden crust. This step enhances the flavor with a bit of caramelization.
Transfer the seared chicken and the sautéed vegetables to the slow cooker. Pour in the chicken broth and add the bay leaf. Give everything a gentle stir to combine the flavors.
Cover the slow cooker with its lid and set it to low. Let the stew cook for 6 hours, or until the chicken is fall-apart tender and the vegetables are soft and flavorful.
Once cooked, remove the chicken thighs and shred the meat using two forks. Discard the bay leaf since it's used for flavoring only.
Return the shredded chicken to the slow cooker, stirring to combine. Taste the stew and adjust salt and pepper as needed. Let it cook uncovered for another 10 minutes to meld the flavors.
Serve the hearty fall chicken stew hot, with a side of crusty bread or over rice for a complete meal. The stew will be thick, fragrant, and filled with tender, shredded chicken and roasted vegetables.