Toss spaghetti in flour to separate strands then shake off any excess flour.
Cook spaghetti for 3-4 minutes in a medium/ large pan of boiling water, add about 1 tablespoon of salt per litre of water, and a few drops of olive oil. Stir regularly with fork to prevent sticking.
Whilst the spaghetti is cooking, empty pesto into separate pan and heat up.
Once the spaghetti is ready, before draining add 1 tablespoons of boiling pasta water (2 tablespoons for double portion) to the pesto, this will add to the flavour.
Drain spaghetti and then add to the pesto.
Top with parmesan and serve. Buon Appetito!