In a large skillet, heat olive oil over medium heat. Add the chopped onion and minced garlic, sautéing until the onion is translucent, about 3-4 minutes.
Transfer the sautéed onion and garlic to the slow cooker. Add the chicken, carrots, potatoes, chicken broth, thyme, rosemary, paprika, salt, and pepper. Stir to combine.
Cover and cook on low for 6-8 hours or on high for 3-4 hours, until the chicken is tender and the vegetables are cooked through.
If you prefer a thicker stew, mix the cornstarch with water in a small bowl to create a slurry. Stir the slurry into the stew about 30 minutes before serving, and let it cook on high until thickened.
Taste and adjust seasoning if necessary before serving.