Heat oil and butter in large saucepan over medium heat. Add onion, garlic and pepper flakes and cook until softened, about 4 minutes. Carefully add vodka and simmer until reduced by about half, about 5 minutes. Cook pasta according to package directions; drain. Meanwhile, stir tomato sauce into onions in saucepan and bring to a simmer. Simmer on medium-low heat 10 minutes. Stir in cream and remove from heat. Toss sauce with pasta, topped with cheese and basil, if desired.