In a large pot or deep skillet, add the diced onion and minced garlic. Sauté over medium heat for about 3-4 minutes until the onion becomes translucent.
Add the crushed tomatoes, vegetable broth, and dried herbs (oregano, basil, and red pepper flakes) to the pot. Stir to combine.
Bring the mixture to a gentle simmer and then add the pasta to the pot. Stir well, ensuring the pasta is submerged in the liquid.
Cook the pasta according to the package instructions, typically 10-12 minutes, stirring occasionally to prevent sticking.
Once the pasta is cooked and most of the liquid is absorbed, reduce the heat to low and stir in the heavy cream. Mix well until the sauce is creamy and smooth.
Add fresh spinach to the pot and stir until wilted. Sprinkle in the grated Parmesan cheese, and mix until melted and fully incorporated.
Season with salt and pepper to taste, adjusting the flavors as needed.
Serve hot, garnished with fresh basil leaves and additional Parmesan if desired.