In a large pot over medium-high heat, add the ground beef and chopped onions. Cook, breaking the meat apart, until the beef is browned and the onions are soft. Drain off any excess grease before moving to the next step.

Add the minced garlic to the browned beef and onions in the pot. Sauté for 1-2 minutes until the garlic is fragrant, being careful not to burn it.

Pour in the marinara sauce, dried oregano, kosher salt, black pepper, and chicken broth. Stir well to combine. Bring the mixture to a simmer and cook uncovered for about 10 minutes, allowing the flavors to develop. I like to let it go the full 10 minutes, as the sauce thickens up nicely.

Break the dry spaghetti noodles in half and stir them directly into the simmering sauce. Make sure the noodles are submerged as much as possible. Cook at a simmer for 12-15 minutes, stirring frequently to prevent the pasta from sticking together or to the pot. Check the noodles after 12 minutes and continue cooking for 1-2 minutes more, if needed, until they are al dente.

Once the pasta is al dente and the sauce has thickened, remove the pot from the heat. Serve the spaghetti hot, topped with grated Parmesan cheese. I always finish with a generous sprinkle of Parmesan for extra flavor—feel free to add fresh parsley as a garnish if you like.