In a large pot or Dutch oven, heat the olive oil over medium heat. Add the diced onion and cook for 2-3 minutes until slightly softened.
Add the minced garlic and cook for an additional minute until fragrant.
Increase the heat to medium-high and add the ground beef. Cook, breaking it up with a wooden spoon, until browned and cooked through, about 5-7 minutes. Drain any excess fat if necessary.
Stir in the beef broth and ranch dressing mix. Bring the mixture to a simmer.
Once simmering, add the pasta. Stir well to combine and ensure the pasta is submerged in the broth.
Cover the pot and reduce the heat to medium-low. Cook for 10-12 minutes, stirring occasionally, until the pasta is cooked al dente and the liquid has thickened.
Remove the pot from heat and stir in the shredded cheddar cheese until melted and creamy. Season with salt and pepper to taste.
Serve hot, garnished with chopped fresh parsley if desired.