Preheat the oven to 375F. Heat the olive oil over medium heat in a large, deep, ovenproof sauté pan that has a tight-fitting lid (you can substitute a Dutch oven). Add the onions and garlic and cook for about 5 minutes, until the onions are translucent. Add the red pepper flakes and dried oregano and cook for 1 more minute. Add the vodka and simmer for 5 to 7 minutes, until the mixture is reduced by half.
Drain the tomatoes through a sieve and crush them into the pan with your hands or using a handheld potato masher. Add the salt and black pepper. Cover the pan with its lid and place it in the oven for 1 1/2 hours. Remove the pan from the oven and let cool for 15 minutes.
Bring a large pot of salted water to a boil and cook the pasta al dente. Drain and return to the pot.
Place the tomato mixture and the cashew cream into a blender and purée in batches until the sauce is completely smooth and creamy. (Careful while you blend, since hot liquids like to splatter.) Add most of the sauce to the pot with the cooked pasta, along with one tablespoon of the fresh oregano. Heat the pasta and sauce over low heat for about 5-8 minutes, or until the pasta has absorbed the sauce and thickened up. Add the remaining sauce as needed; I usually end up using all of it, but I add most of it at the beginning and the rest as I heat and stir.
Divide the pasta onto plates and top each with a sprinkle of fresh oregano and a tablespoon of your vegan parmesan. Enjoy!