In a large pot, bring salted water to a boil. Add the rotini pasta and cook according to package instructions until al dente. Drain and set aside.
While the pasta is cooking, heat the olive oil in a large skillet over medium-high heat. Add the ground beef and cook until browned, breaking it apart with a wooden spoon.
Stir in the taco seasoning and cook for another minute, allowing the spices to coat the meat.
Add the can of diced tomatoes (with juice) and the beef broth to the skillet. Bring the mixture to a simmer.
Reduce heat and let it simmer for about 5 minutes, allowing the flavors to meld together.
Stir in the cooked pasta to the meat mixture, making sure everything is well combined.
Remove the skillet from heat and add both the cheddar and mozzarella cheese. Mix until the cheese is melted and creamy.
Season with salt and pepper to taste.
Serve hot, garnished with chopped cilantro and a dollop of sour cream if desired.