Saute garlic and pepper flakes over a medium heat until golden brown. Add tomatoes. Once the sauce comes to a boil, lower the heat and simmer for 15 minutes. In another pot, you should boil the penne to al dente. Drain and put back into the hot pot. After the 15 minutes is up on the sauce, add the cream and Vodka. Bring to a boil and heat through for one minute. Add sauce to the pot with the penne. Add parsley and stir.