In a large pot, drizzle olive oil over medium heat.
Once thoroughly heated, stir in the onions. Once softened, add the ground beef. Cook, stirring to break the beef into small pieces, until browned. Stir in the garlic and cook for 30 seconds. If needed, drain any excess liquid.
Stir in the chicken broth, tomato sauce, and water. Bring the mixture to a boil, then reduce heat to a simmer and add the spaghetti noodles. Cover and cook, stirring occasionally to keep the bottom from sticking, until most of the liquid has been absorbed and noodles are al dente, just tender, 17-20 minutes. If too much liquid has evaporated before the pasta is done, add a little more water.
Stir in the parmesan and remove from heat. Serve immediately with additional parmesan and fresh parsley if desired.