Heat oil in a pan, cook the sausage. Strain, leave the oil in the pan, and set the sausage aside. (You only need a couple of tablespoons of oil; if it's too greasy, like say you used bacon, you can dump some of it out).
Add butter (and a little more oil in the pan if needed). Add the onion, garlic, and chili flakes. Cook the on low heat until they are softenned, about 10 minutes. Be careful not to let the onions burn. Turn the heat down if they start to fry.
Add tomato paste and mix it well into the onion/garlic on low to medium-low heat for a 2-3 minutes. Pay attention to the tomato paste, and stir as needed to keep from burning it.
Add the tomatoes (and all its liquid) and incorporate into the tomato paste mixture. Add water as needed if the mixture is too thick (this will depend on how much liquid came with the tomatoes. You may need to add 1/2 cup to 1 cup; there is a lot of tomato paste so it's pretty forgiving. Simmer the tomatoes for about 10 minutes on low.
Keeping the heat low, add the cream and mix it through. If the temperature is too high, your cream might break, so make sure everything has been on low heat. If you are unsure, add the cream slowly, a little bit at a time. If it looks like it is separating or getting "grainy", turn off the heat and let the tomatoes cool for a bit then try again.
After mixing all the cream through, transfer the sauce into a blender and blend until smooth. If you are using a deep enough pot, you may be able to use an immersion (hand) blender. Return the sauce to the pan.
In the meantime cook the pasta until just short of al dente, following the instructions on the box. Reserve a cup of the pasta cooking water and drain.
Bring the sauce back to a low simmer and add the vodka about 4-5 minutes before adding your pasta. If you time it right, you can do this as your pasta is cooking.
Add the pasta to the sauce and combine. Add the pasta water a little at a time until you achieve your desired consistency. Let your pasta finish cooking in the sauce for 2-3 minutes or until your pasta is cooked to your liking.
Add the cooked sausage back into the pan. Stir well to combine. Taste and adjust for salt and pepper.
Serve while hot,topped with grated pecorino romano or parmesan! Enjoy!
