Preheat oven to 350ºF. Lightly spray a 9×13-inch pan with cooking spray. Set aside.
Cook ground beef in a large skillet until no longer pink. Drain fat. Stir in taco seasoning, diced tomatoes and cheese packets. Simmer for 5 minutes.
Spread mixture into prepared pan.
Bake for 30 to 40 minutes, until bubbly.
