In a large frying pan heat the pancetta with a tablespoon of olive oil; take care not to burn it but bring it to a light crisp. Put a bit of pancetta to the side to garnish the plate.
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 tonnarelli
Cook for 3 – 4 minutes depending on preference
Put the pesto in a pan with the pancetta and transfer the tonnarelli 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 trofie)
Stir the pesto into the tonnarelli gently and plate with Parmesan and the remaining Pancetta on top as a garnish