Bring a large pot of well salted water to a boil.
Melt the butter in a Dutch oven over medium heat. Add the onion, garlic, and crushed red pepper flakes and cook, stirring often, until onion is softened.
Add the tomato paste and cook, stirring, about 3 minutes. Stir in the whole tomatoes. Bring to a simmer, then cook, stirring often and crushing the whole tomatoes roughly with a spoon, until sauce has thickened slightly, about 10 minutes.
Stir in 1 cup cream. Transfer sauce to a blender, and blend until very smooth (or use an immersion blender). Return the sauce to the pot and stir in the vodka and season with salt and pepper.
Add the pasta to the boiling water and stir well. Cook until al dente, according to package directions. Drain well and serve with the sauce and grated Parmesan.