Bring a large pot of water to a boil and cook the macaroni and cheese according to the package instructions, including the milk and butter. Once cooked, set aside.

While the macaroni cooks, heat a large skillet over medium heat. Add the ground beef and cook, breaking it up with a spoon, until browned and fully cooked. Drain any excess grease.

Stir the taco seasoning into the cooked ground beef, along with 1/4 cup of water. Cook for 1-2 minutes, stirring occasionally, until the seasoning is evenly distributed and the mixture thickens slightly.

Add the can of diced tomatoes and green chilies (do not drain) to the skillet with the seasoned beef. Stir to combine and heat through for 2-3 minutes.

Once the macaroni and cheese is ready, add it to the skillet with the beef and tomato mixture. Stir everything together until well combined and heated through.

Serve immediately, garnished with your favorite taco toppings if desired, such as shredded cheese, sour cream, or chopped cilantro. Enjoy!