Cook the pasta according to pack instructions, then drain, reserving 100ml of the cooking water.
Tip the cooked pasta into a large bowl along with the reserved cooking water. Add the soft white cheese and pesto and stir through, until the pasta is coated all over with the sauce.
Add the grated courgettes and combine thoroughly. Set aside for about 30 minutes to let cool to room temperature (no need to chill).
Just before serving, stir through herbs and season.