In a large Dutch oven, heat olive oil over medium-high heat.
Add ground beef and chopped onion, cooking until fully cooked and no longer pink.
Add minced garlic and cook for an additional minute until fragrant.
Drain excess fat and return the meat mixture to the pan. Add taco seasoning, tomatoes, spaghetti noodles, and water.
Bring to a boil, cover, then reduce heat to a slow simmer. Cook for 15-20 minutes or until the noodles are tender, stirring occasionally to prevent sticking.
Remove from heat, top with 1 ½ cups of shredded cheese and ¼ cup cilantro. Stir until the cheese is melted into the spaghetti.
Sprinkle the remaining cheese and cilantro on top.
Serve with desired toppings.
Notes
While it's best eaten fresh, you can store leftovers in an airtight container for up to 3 days. Reheat gently on the stove, adding a bit of water, if needed to loosen things up.