In a large pot or deep skillet, combine the dried spaghetti, vegetable broth, water, sliced onion, minced garlic, dried oregano, dried basil, crushed red pepper flakes, salt, and black pepper.
Drizzle the olive oil over the ingredients in the pot.
Bring the mixture to a boil over medium-high heat, stirring occasionally to prevent the pasta from sticking.
Once boiling, reduce the heat to medium and continue to cook, stirring frequently, until the pasta is al dente and most of the liquid has been absorbed, about 10-12 minutes.
Remove the pot from heat and stir in the grated Parmesan cheese until melted and the sauce becomes creamy.
Sprinkle the chopped fresh parsley over the pasta and gently toss to combine.
Serve immediately.