Preheat the oven to 200°C /Fan 180°C/Gas 6. Place the pastry sheet, on the baking paper it comes with, on a baking tray. Score a border about 1.5cm wide around the edges of the pastry and brush olive oil all over the pastry within the border.
Place the sweet potato slices in a mixing bowl, add a good drizzle of olive oil and season generously with salt and pepper. Using your hands, give them a mix to ensure the slices are all lightly coated in oil but not overly greasy.
Arrange the slices, slightly overlapping, on the pastry sheet within the border. Season well with salt and pepper and drizzle with a little more oil. Crumble over the feta, scatter with the chilli and dot the sage leaves on top. Bake for 25–30 minutes until nicely browned. Remove from the oven, drizzle with honey and serve.