Squeeze as much liquid as possible out of the thawed spinach - any excess water will make the phyllo soggy. Keep the unused phyllo sheets under a damp kitchen towel while you assemble, so they don't dry out and crack. For a vegetarian (non-vegan) version, swap the smoked tofu for ricotta and the vegan butter for regular butter. Best served warm; leftovers keep in the fridge for up to 3 days and crisp back up in the oven at 180°C for 8-10 minutes.