In a large pot or deep skillet, heat the olive oil over medium heat.
Add the chopped onion and sauté for 3-4 minutes until translucent.
Add the minced garlic and cook for another 1 minute until fragrant.
Pour in the vegetable broth, water, and heavy cream, then stir to combine.
Add the spaghetti to the pot, making sure the noodles are mostly submerged in the liquid.
Sprinkle in the dried oregano, dried basil, salt, black pepper, and red pepper flakes.
Bring the mixture to a boil over medium-high heat.
Once boiling, reduce the heat to medium-low and simmer uncovered, stirring occasionally, until the pasta is cooked al dente and the liquid has mostly absorbed, about 12-15 minutes.
Remove the pot from heat and stir in the grated Parmesan cheese until melted and well combined.
Sprinkle the chopped fresh parsley over the pasta and serve immediately.