Empty the chopped tomatoes and the basil leaves into a blender / food processor and blitz until relatively smooth.
Place the pasta in a saucepan of boiling, salted water and cook as per the packet instructions, then drain. While the pasta is cooking continue to make the sauce.
Heat the olive oil in a medium sized saucepan and sauté the onion and garlic for about 5 minutes until soft.
Add the tomatoes and stir in the chilli powder. Gently simmer the sauce for about 10 – 15 minutes until it has thickened to a desired consistency.
Season to taste.
Add the drained pasta to the sauce and combine well.
Divide the pasta Arrabiata between bowls and serve garnished with grated parmesan cheese.
Serve with a fresh green salad of lettuce, cucumber and spring onions.