Bring a large pan of water to the boil. Cook the pasta for as long as the packet says.
Drain the pasta, then tip the pasta back into the pan on a low heat. Add the pesto, then half fill the pesto jar with water, put the lid on and shake, then pour that into the pasta too. Add the olives and chopped feta.
Cook, stirring often, until the pesto has warmed through - just a couple of minutes will do it. Be careful not to cook for too long or your pasta will stick to the bottom. Done!