This recipe is inspired by a pie served at Trattoria alle Vignole, one of my favourite restaurants in Venice. Whenever I bake this, I can’t help but think of lazy summer lunches there, at the picnic bench under the big shady tree where we always sit looking out on to the lagoon. I sometimes add a few saffron-hued courgette flowers on top because they look beautiful, but they are by no means essential.