4 tablespoons (½ stick) unsalted butter
3 garlic cloves, minced
1 medium yellow onion, diced
2 tablespoons tomato paste
½ cup vodka
1 (28-ounce) can crushed tomatoes
1 cup heavy cream
Generous pinch of red pepper flakes
1 teaspoon salt
2 tablespoons slivered fresh basil, plus additional for serving
1 pound penne pasta
½ cup finely grated parmesan cheese, plus additional for serving
Cook pasta in well salted water until al dente. Reserve ½ cup of cooking water, drain pasta and set aside.
While the pasta is cooking, melt the butter in a large skillet set over medium-high heat. Add the onion and cook, stirring occasionally, until softened, about 6 minutes. Add the garlic and continue cooking until fragrant, about a minute more. Stir in tomatoes and their juices. Bring to a simmer. Reduce heat to medium and stir in the tomato paste and vodka. Cook until most of the alcohol has evaporated, at least 5 minutes.
Stir in cream, red pepper flakes and salt. Bring to a a simmer, then reduce heat to medium-low. Cook sauce until thickened, about 5 minutes. Taste and adjust seasoning as needed. Stir in basil and cheese.
Add pasta to skillet and toss to coat, adding pasta water as needed to thin the sauce. Serve topped with additional basil and parmesan.