Preheat oven to 375˚F (190˚C).
Drizzle the olive oil in a large, oven proof pan over medium heat.
Once heated, add the onions and cook, stirring occasionally, until they begin to soften and become translucent, about 5 minutes. If needed, add a little more olive oil.
Stir in the garlic, dried oregano, and red pepper and cook for another minute.
Pour in the vodka, scraping the bottom and sides of the pan to remove any browned pieces, and cook, stirring occasionally, until reduced by half.
Crush the peeled tomatoes into the pan. Sprinkle with salt and pepper, cover, and place in preheated oven. Cook for 1 1/2 hours, stirring around halfway through the cooking time.
Remove from oven and allow to cool for 15 minutes. Blend using an immersion blender or carefully transfer to a stand blender to blend until smooth.
In a large pot, bring water to a boil. Add pasta and cook until al dente, just tender. Drain and set aside.
Pour the tomato sauce back into the pan and place over medium heat.
Stir in the heavy cream and chopped parsley. Adjust seasonings to taste, adding more salt and pepper if needed and simmer for 10 minutes, stirring occasionally.
Fold in the tender pasta and cook just until heated through.
Remove from heat and stir in the freshly grated parmesan.
Serve immediately with additional Parmesan and parsley.