Begin by cooking the macaroni according to the package instructions in a large pot. Drain and set aside.
In the same pot, over medium heat, add the ground beef or turkey, diced onion, and minced garlic. Cook, stirring frequently, until the meat is browned and the onion is translucent, about 5-7 minutes.
Stir in the taco seasoning, diced tomatoes (with their juice), and broth. Bring the mixture to a simmer.
Add the cooked macaroni to the pot and mix thoroughly. Allow it to simmer for an additional 5 minutes to heat through and allow the flavors to meld.
Remove the pot from heat and stir in the shredded cheddar and Monterey Jack cheeses until melted and creamy. If desired, season with additional salt and pepper to taste.
Serve hot, garnished with optional toppings such as sour cream, cilantro, or jalapeños.
For a vegetarian version, consider substituting the meat with black beans or lentils, and feel free to add extra vegetables such as bell peppers, corn, or zucchini.
Adjust the level of seasoning or spice by using mild or spicy taco seasoning according to your preference.