Add the chicken breasts, diced tomatoes, tomato sauce, garlic, Italian seasoning, salt and pepper to the crock pot.
Cover and cook on low for 4-6 hours on low or 3 hours on high.
Combine the cornstarch and heavy cream together in a small mixing bowl. Stir this mixture into the crock pot for the last 30 minutes of the cook time.
Stir in the fresh basil and serve!
We serve this either over pasta or rice.
