1Bring a large pot of salted water to a boil. Cook the rigatoni according to package instructions until al dente. Reserve 1/2 cup of pasta water, then drain the pasta.
2While the pasta cooks, finely chop the garlic, shallot, and parsley.
3In a large skillet over medium heat, add olive oil. Sauté the shallot and garlic until fragrant and softened, about 2-3 minutes.
4Add the tomato paste and red chili flakes to the skillet. Cook, stirring, for 2-3 minutes until the tomato paste darkens.
5Pour in the vodka and cook for 2-3 minutes, allowing the alcohol to evaporate.
6Reduce the heat to low and stir in the heavy cream. Mix until the sauce is smooth and creamy.
7Add the butter and half of the grated Parmesan cheese. Stir until melted and combined.
8Season with salt and freshly ground black pepper to taste.
9Add the cooked rigatoni to the sauce, tossing to coat. If the sauce is too thick, add reserved pasta water a little at a time until desired consistency is reached.
10Serve hot, garnished with the remaining Parmesan cheese and fresh parsley.