Step by step

Boil the conchiglioni until ‘al dente’, adding a little oil to the water in order to prevent the pasta sticking

Tips
To make your pesto sauce, you can use a food processor with plastic blades, since these prevent the oxidation of the leaves (unlike metal blades).
Trivia
To avoid getting a bitter or overly strong tasting pesto sauce, use basil leaves that have been well dried and above all are intact.