This was a difficult recipe to nail - but there were plenty of enthusiastic researchers and tasters! Happy days all round.
Our final recipe comes to you all but cooked, requiring only a final blast of heat to melt the Gruyere and heat the dish through. We peel and slice the potatoes before parcooking in cream flavoured with garlic, Parmesan, mustard, thyme and and nutmeg. After blast-chilling we top the gratin with shredded Gruyere and seal.
Defrost information: Cook straight from frozen or defrost overnight in the fridge; once defrosted, keep refrigerated and cook within 48 hours.