Cook the pasta until it is al dente and reserve.
In a large sauté pan or sauce pot, melt the butter over medium heat and then add the finely chopped onion. Sauté the onion until it is soft, about 5 minutes.
Once the onions are soft, but not colored, add the minced garlic and cook for another 2 minutes.
Add the tomato sauce, vodka, and crushed red pepper flakes and bring to a low simmer. Cook for about 10 minutes, allowing the sauce to slightly reduce and the alcohol flavor to mellow.
Stir in the cream and the salt bring back to a very low simmer. Do not allow the sauce to boil or the cream and tomato could separate.
Check the seasoning and adjust as needed.
Combine the sauce with the cooked pasta. Serve with grated parmesan or pecorino cheese.