I realise that we have thus far only considered the crust as a separate entity, which is of course toroidal (and for which we should evidently add a new form to the model for - I would propose the 'doughnut'), however the full pizza with a stuffed crust is not - it has no hole. By compressing the centre of a calzone until the top and bottom faces meet we reach the full stuffed crust pizza. Perhaps we've been wrong all along...