To a 3-4 quart slow cooker, add cooked beef mixture, beef broth, cornstarch, taco seasoning, and diced tomatoes with green chiles. Stir to combine well.
Cover and cook on HIGH for 3 hours, or LOW for about 5 hours. Remove lid, add half the shredded cheese, give it a stir, top with remaining cheese.
Cover and cook on LOW for 10 minutes, or until cheese is melted on top.
Sprinkle with garnishes and serve with tortilla chips!