2 packages (7-1/4 ounces each) macaroni and cheese dinner mix
2 pounds ground beef
1 small onion, chopped
1 can (14-1/2 ounces) diced tomatoes, undrained
1 can (10 ounces) diced tomatoes and green chiles, undrained
1 can (8 ounces) tomato sauce
2 tablespoons chili powder
1 teaspoon garlic salt
1/2 teaspoon ground cumin
1/4 teaspoon crushed red pepper flakes
1/4 teaspoon pepper
2 cups sour cream
1-1/2 cups shredded Mexican cheese blend, divided
Preheat oven to 350°. Set aside cheese packets from dinner mixes. In a large saucepan, bring 2 quarts water to a boil. Add macaroni; cook until tender, 8-10 minutes.
Meanwhile, in a Dutch oven, cook and stir beef and onion over medium heat until beef is no longer pink, 8-10 minutes; drain. Stir in tomatoes, tomatoes and green chiles, tomato sauce and seasonings. Drain macaroni; add to beef mixture. Stir in contents of cheese packets, sour cream and 1 cup cheese.
Transfer to a greased 13x9-in. baking dish; top with remaining cheese. Bake, uncovered, until bubbly, 20-25 minutes.