Oven cook from chilled. Preheat oven to Electric 220°C, Fan 200°C, Gas Mark 7.
Remove lid and stir ingredients so evenly distributed across the foil tray. Melt 30g of butter and lightly brush sheets of filo, roughly scrunch and arrange on top of gratin. For best results, only open the packet of pastry immediately before use. Place on a preheated baking tray, on the middle shelf of the oven, for 25 minutes. Check food is piping hot before serving. All cooking appliances vary. This is a guide only.
Keep refrigerated, once opened consume within 24 hours and do not exceed the use by date. Not suitable for home freezing.