Heat the oil in a frying pan on a medium heat.
Fry the onions for 5 minutes until softened.
Add the garlic, tomatoes and thyme. Cook for 10 minutes.
Add the tomato paste and simmer for 15 minutes.
Stir in the olives, basil and season with salt and pepper.
Remove the chicken from the oven and pour off any juices from the tin.
Spoon the tomato sauce around the chicken.
Return the chicken to the oven and roast for 50-60 minutes.
At the last 20 minutes of the roasting time remove the chicken from the over, baste the chicken with the tomato sauce and crumble the feta cheese over the tomato sauce.
Return to the oven for the final cooking time. Ensure that the chicken is cooked by piercing the thigh and checking the juices are clear.
Remove the chicken, cover with foil and let rest for 10 minutes.
Carve the chicken for serving and if necessary, reheat the tomato sauce.