Bring a large pot of water to a boil, salt it generously and cook the pasta al dente according to the instructions on the package. Reserve a cup of pasta water before draining.
Meanwhile, heat the olive oil in a large deep pan or a Dutch oven and cook the chicken breast for 4-5 minutes over medium-high heat until no longer pink (or until slightly golden if you like).
Stir in the onion, garlic and red chilli flakes and continue to cook for another minute.
Add the tomato paste and chopped tomatoes and stir to combine. Add a bit of pasta water if it looks too thick. Season to taste and bring to a simmer. Lower the heat and simmer for 10 minutes until the sauce thickens.
Transfer the cooked pasta to the pot and stir in the Parmesan and basil. Serve immediately with extra grated Parmesan on top if you like.
