Spaghetti Alla Vodka with Mussels

1.Bring a large pot of salted water to a boil. Heat olive oil in a dutch oven over medium-high heat. Add the onion and cook, stirring, until softened, 5 minutes. Stir in the garlic and red pepper flakes and cook for 30 seconds. Stir in tomato paste and cook for 1 minute. Add the tomatoes and their juices and 1/2 teaspoon salt. Bring to a boil, then reduce the heat and simmer, stirring occasionally, until thickened, 15 minutes.
2.Add the heavy cream to the sauce and simmer until thickened, 3 minutes. Stir in vodka, add mussels, cover and cook until the mussels open, about 5 minutes. Remove from the heat; keep the pot covered.
3.Add the spaghetti to the boiling water and cook as label directs for al dente. Reserve 1 cup cooking water, then drain. Add the spaghetti to the pot with mussels, along with 1/4 cup cooking water. Cook over medium heat, tossing and adding more cooking water until spaghetti is well coated. Season with salt.
4.Divide the spaghetti and mussels among shallow bowls. Sprinkle with the parsley and more red pepper flakes.