Bring a pot of salted water to a boil. Cook your pasta according to the package instructions. Drain your cooked pasta, and set aside.
In a large skillet, Add the olive oil, onion, garlic, and salt. Place over medium heat, and cook for 2 to 3 minutes over medium heat, or until the onion turns translucent and softens.
Move the skillet off the heat (to prevent flare ups!) and carefully add your vodka. Return to medium heat and cook for another 2 to 3 minutes, or until the vodka reduces by about half.
Add the tomato sauce, and bring the mixture up to a boil. Simmer for about 5 minutes just to cook out any raw tomato flavor. *** (see notes) Pour in the heavy cream and stir to incorporate. Taste for seasoning and salt if needed. If you'd like the sauce to be spicy, add in a pinch of red pepper flakes (to taste).
Toss the pasta in vodka sauce until all the pasta is coated. (Optional) Top with grated Parmesan cheese and/or chopped parsley.