This simple pasta dish is relatively quick to make, but it feels quite elevated. Finishing the spaghetti in the sauce the mussels cooked in adds a layer of flavour perfect for a special occasion (or even just a weeknight).
Bring a large pot of salted water to a boil. Meanwhile, add the olive oil and chili flakes to a large pot and set over medium heat. Once shimmering, add the shallot and a generous pinch of salt and cook, stirring occasionally, until softened - about 3 minutes.
Add the garlic and tomato paste and cook, stirring, for 1 more minute. Add the tomatoes along with another pinch of salt and cook for about 5 minutes, or until the tomatoes begin to break down and release their moisture.
Pour the wine over the tomatoes and cook until the strong alcoholic smell has gone, 1-2 minutes. Then, add the mussels all at once and cover the pot. Cook until the mussels have all opened wide - about 7-10 minutes.
Add the pasta to the boiling water and cook for 2 minutes less than the package suggests. Do not drain - or if you do drain, reserve roughly 120-250 ml (½-1 cup) of the cooking water. Use a slotted spoon to remove the mussels from the pot and set them aside. Use tongs to lift the cooked pasta from the cooking water into the pot in which you cooked the mussels. Add the parsley and toss to coat in the sauce, adding a splash of pasta cooking water, if needed, to adjust the consistency.
Serve the pasta, topping with the cooked mussels and more parsley, if desired.