Heat a Dutch oven or large pot over medium-high heat. Add the ground beef and chopped onion and cook, breaking up the beef, until the meat is browned and the onion is softened, about 5–7 minutes.
Add the minced garlic to the pot and cook, stirring, until fragrant, about 1 minute.
Stir in the Rotel tomatoes, tomato sauce, taco seasoning, beef broth, tomato paste, and Worcestershire sauce. Increase heat and bring the mixture to a boil.
Add the spaghetti noodles to the boiling mixture, reduce heat to medium so it simmers, and cook uncovered, stirring frequently and scraping the bottom occasionally, until the pasta is tender, about 15–18 minutes.
About 5 minutes before the pasta is done, stir in the shredded cheddar and Monterey Jack cheeses until melted and evenly combined.
Remove the pot from the heat, garnish with chopped cilantro if desired, and serve immediately.
