Preheat the oven to 200°C, fan 180°C, gas 6. Put the squash onto a baking tray and drizzle with the olive oil. Roast for 20 mins, add the honey and stir to coat, then roast for another 10 mins until slightly golden.
Roll the pastry into a large rectangle and cut in half to make two smaller rectangles, about 12cm x 18cm each.
In a bowl, mix the chopped spinach with the ricotta and the chopped chives. Stir in the lemon zest if using – it adds a really lovely citrussy flavour to the tart.
Spoon the spinach mixture onto the pastry sheets and top with the roasted butternut squash. Bake in the oven for 15-20 mins until the pastry is golden brown and risen.