cook potatoes in large pan of boiling water,20 minutes until tender but not falling apart.Heat oil in pan add onions garlic and other veg and cook over low heat for about 5 minutes until onion has softened.Increase heat to medium add beef or quorn,stirring until browned .Add mushrooms and stock,add sugar and Worcesterchire Sauce ,season with salt and pepper,simmer for about15 minutes. Take of heat and put into ovenproof dish ,let slightly cool.The juices should be gravy like, if not use a little gravy powder to thicken.
Preheat oven to 200 C / gas 6
Drain potatoes add egg , butter and nutmeg,mash thoroughly.Add on top of meat or quorn mixture ,level out and create random pattern with fork turned back to front.
Reheat in oven until potato is crisp and golden brown.