In a 4- to 6-quart slow cooker, combine the diced tomatoes, marinara sauce, minced garlic, salt, Italian seasoning, dried basil, and pepper. Stir well to mix all the ingredients together.
In a small bowl, whisk together the heavy whipping cream and cornstarch until smooth. Pour the cream mixture into the slow cooker, ensuring it blends with the tomato sauce.
Add the chicken breasts to the slow cooker, pressing them down gently into the sauce to coat them well.
Cook on low for 3 to 4 hours, or until a meat thermometer inserted into the thickest part of the chicken reads 165°F.
Stir in the fresh basil, taste the sauce, and adjust seasonings if needed.
Serve the creamy Italian chicken with a sprinkle of grated Parmesan cheese on top for an extra touch of flavor.
For a thicker sauce, you can remove the chicken once cooked and keep the sauce on high in the slow cooker for an additional 15-20 minutes to reduce and thicken.
Notes
For a thicker sauce, you can remove the chicken once cooked and keep the sauce on high in the slow cooker for an additional 15-20 minutes to reduce and thicken.