2 tablespoons olive oil
3 ounces thinly sliced prosciutto, finely chopped (optional)
1/2 medium sweet onion, finely chopped
1 tablespoon tomato paste
3 to 4 cloves garlic, pressed in a garlic press or minced
1 28-ounce can diced tomatoes (I like chef's cut)
1/4 teaspoon red pepper flakes, to taste
2 teaspoons sugar
1 teaspoon kosher salt
1/3 cup vodka
1/2 cup heavy cream
1 pound (16 ounces) penne pasta
Parmesan cheese, for serving
Chopped parsley, for serving
Heat the olive oil in a large Dutch oven over medium-high heat until very hot but not smoking. Add prosciutto and cook, stirring occasionally, until crisp, 4 to 5 minutes. Remove with a slotted spoon and set aside.
Reduce heat to medium. Add the onions and cook until softened and golden-brown, about 5 minutes. Add the tomato paste and garlic, stirring to combine, and sauté for 2 more minutes.
Stir the tomatoes, red pepper flakes, sugar, and salt into the onion mixture. Stir in the vodka and increase heat back to medium-high. Briskly simmer for 8 to 10 minutes, stirring frequently, until the alcohol flavor has cooked off. Reduce heat to low and whisk in heavy cream.
While making the vodka sauce, bring a large stockpot of heavily salted water to a boil. Add pasta and cook, stirring occasionally, until al dente according to package directions. Reserve 1/4 cup cooking water before draining. Gently fold the cooked penne and reserved prosciutto into the vodka sauce and continue cooking on low heat for another couple of minutes. (I actually use a little less than one pound of pasta because I like mine very saucy, but it is easier to just cook the pound and add it to the sauce to taste.) Toss with a bit of pasta water if sauce is too thick.
Season with additional salt and red pepper flakes if desired, and serve with fresh Parmesan and chopped parsley.