In a large skillet over medium heat, cook the ground beef and diced onion until the beef is browned and the onion is softened, about 5-7 minutes. Drain excess grease if necessary.
1 pound ground beef, 1/2 yellow onion
Add the minced garlic and taco seasoning. Cook for 1 minute until fragrant.
3-4 cloves garlic, 3 Tablespoons taco seasoning
Stir in the diced tomatoes with chilis and beef broth. Bring to a simmer.
1 (14.5-ounce) can diced tomatoes with chilis, 1 1/2 cups beef broth
Break the spaghetti noodles in half and add them to the skillet. Stir to combine, ensuring the noodles are mostly submerged.
8 ounces spaghetti noodles
Cover and cook for 10-12 minutes, stirring occasionally, until the pasta is tender and most of the liquid is absorbed.
Remove from heat and stir in the shredded cheddar cheese until melted and creamy.
1 cup freshly grated cheddar cheese
Serve warm with optional toppings like chopped cilantro, diced tomatoes, chopped green onions, or sour cream.