In a saucepan over medium high heat, cook and crumble sausage until cooked through. Set aside.
In a food processor, puree half of the diced tomatoes until smooth. Combine pureed and diced tomatoes, including juices.
Heat oil in a large heavy saucepan over medium. Add onion and tomato paste, stirring, until onion is light golden, 3 min.
Add garlic and red pepper flakes, stirring, 30 seconds. Stir in the tomatoes with juice and 1/2 tsp salt. Remove pan from heat and add vodka. Return pan to medium high and simmer 8 -10 minutes, stirring often and lowering heat if simmering is vigorous. Stir in cream and cooked sausage and cook to heat up 1 min. Turn heat off and keep warm.
While sauce is simmering: bring large pot of well salted water to boil. Cook pasta until just shy of al dente (about a minute less than package instructions for al dente) Reserve 1/2 up of pasta water. Drain pasta but don't rinse, and return it to the pot.
Add the warm tomato sauce mixture and toss over medium heat, until pasta absorbs some of the sauce, 1-2 min. Adjust consistency of sauce with the reserved pasta water as needed.
Stir in basil, season with salt and pepper to taste, and serve with fresh parmesan.