Place the vegetables in the bottom of a 6 quart slow cooker. Pour in the chicken broth, then add the Italian seasoning, bay leaf, salt and 1/4 teaspoon pepper and add the tomato paste.
Sprinkle chicken with a little salt and pepper then add to the slow cooker on top of the vegetables.
Cover and cook on LOW for 6 hours or on HIGH for 4 hours, or until vegetables are tender and chicken is cooked through.
About 15-30 minutes before serving, whisk together cornstarch and milk in a small bowl until cornstarch is dissolved. Pour into the slow cook and gently stir until combined. Cover and turn to low or warm setting until ready to serve (within 30 minutes).
Refrigerating: Cool completely and store in an airtight container in the fridge for up to 4-5 days.
Freezing: Cool completely and store in airtight freezer safe containers and freezer for up to 4-6 months. Keep in mind that the texture of the veggies and potatoes may be a little mushy upon thawing. Thaw before reheating.
Reheating: I recommend reheating in a small saucepan on the stove top. You can also microwave for 60-90 second, stirring halfway through.
To make on the stove top, heat melt some butter and saute the vegetables. Add the herbs and seasonings and saute for another minute. Add the broth and bring to a boil, then add the chicken and potatoes. Reduce to a simmer and cover and cook for about 20-30 minutes or until chicken and potatoes are cooked through. Add cornstarch slurry and heat for an additional 5-10 minutes.