Chicken arrabiata

2 large chicken breasts, skin removed
4 tbsp olive oil
4 large garlic cloves, finely chopped
½ small bunch fresh curly or flatleaf parsley, finely chopped, plus extra to serve (optional)
1 tsp chilli flakes
2 x 400g tins chopped tomatoes
1 tbsp granulated or caster sugar
400g penne pasta
salt and freshly ground black pepper
15g Parmesan, grated, to serve

Season the chicken all over with salt and pepper. Heat 2 tablespoons of the oil in a heavy-bottomed frying pan. Add the chicken breasts and fry over a medium–high heat until just golden brown on the outside – they will cook through later. Lift from the pan onto a plate to catch any juices.
Mix the garlic and parsley together in a small bowl. Add the rest of the oil to the pan with the garlic and parsley mixture and chilli flakes. Turn the heat down and sizzle together for about 30 seconds until really fragrant, but do not let the garlic brown. Quickly mix in the tomatoes and sugar. Quarter fill each can with water to rinse out the last of the tomato sauce and tip this all into the pan too.
Squish the chicken breasts back down into the sauce and simmer gently for 8–10 minutes, turning the chicken over halfway through. Check the chicken is cooked through and lift from the sauce onto a chopping board. Cook the sauce for about 10 minutes until it is thick and the top is glistening with oil. Taste to see if it needs more seasoning and keep warm. Slice the chicken breasts and return to the sauce.
Meanwhile, bring a large saucepan of water to the boil. Tip the pasta into the boiling water and cook for 9–11 minutes or until cooked to your liking. Drain the pasta thoroughly and combine with the sauce.
To serve, scatter over some parsley, if using, and top with Parmesan.