n a Heavy, large skillet, simmer the marinara sauce and vodka over low heat, stirring often, until the mixture reduces by one fourth, about 20 minutes. Stir in the cream and continue to simmer over low heat until the sauce is heated through. Remove the skillet from the heat and stir in the Parmesan, ½ teaspoon of salt, and ¼ teaspoon of pepper. Season the sauce with more salt and pepper to taste.