In a large sauce pan add 1 litre of salted water for every 100g of pasta. For 250g of pasta add 2.5 litres of water.
Bring the water to a gentle boil and put in the ravioli.
Cook for 3 – 4 minutes depending on preference.
Put the pesto in a pan and transfer the ravioli using a slotted spoon making sure that some of the starchy pasta waster makes into the pan with the pesto. (The starchy pasta water is the secret to getting a good coating of the pesto on ravioli).
Stir the pesto into the ravioli gently and plate with Parmesan on top as a garnish.