Cook the Ground Beef: In a large skillet over medium heat, cook the ground beef (or turkey) until browned and fully cooked. Drain any excess fat. Add the chopped onion and minced garlic, and sauté for another 2-3 minutes until the onion is softened.

Add Taco Seasoning: Sprinkle the taco seasoning over the cooked meat and stir to coat evenly. Add the can of diced tomatoes with green chilies (including the liquid) and the beef broth. Stir to combine.

Cook the Pasta: Add the uncooked pasta to the skillet, making sure it is submerged in the liquid. Bring the mixture to a boil, then reduce the heat to low, cover, and simmer for about 10-12 minutes, or until the pasta is cooked and the liquid is mostly absorbed.

Add Cheese and Milk: Once the pasta is tender, stir in the milk, shredded cheddar cheese, and shredded mozzarella cheese. Stir until the cheese is melted and the sauce is creamy.

Finish with Sour Cream: Remove the skillet from the heat and stir in the sour cream. Taste and adjust the seasoning with salt and black pepper, if needed.

Serve: Garnish with fresh cilantro or chopped green onions if desired. Serve the cheesy taco pasta hot.