In a large pot, heat the olive oil over medium heat. Add the minced garlic and sauté for about 1-2 minutes until fragrant but not browned.
Pour in the vegetable broth and bring it to a rolling boil.
Add the spaghetti to the pot, making sure it's submerged in the broth. Cook according to package instructions, usually around 8-12 minutes, stirring frequently to prevent sticking.
Once the pasta is al dente and the broth has reduced, lower the heat and stir in the heavy cream, Italian seasoning, and red pepper flakes, if using.
Gradually mix in the grated Parmesan cheese, stirring continuously until the sauce is creamy and coats the pasta evenly.
Season with salt and pepper to taste. If the sauce is too thick, add a splash of broth or water to reach desired consistency.
Remove from heat and let sit for a couple of minutes to thicken slightly.
Serve immediately and garnish with fresh chopped parsley and extra Parmesan if desired.
Notes
Add more broth or water if the sauce is too thick.