We have on Christmas day with turkey but equally good with duck, lamb, pork or beef.
Combine all filling ingredients and cook in slow cooker - 8 hours low, 4 high
Once completed, if a little too watery, add 2 tsp cornstarch or arrowroot (tapioca flour) powder (combine/mix in 3/4 cup water)
Preheat oven to 180 degrees C/350 F. Meanwhile, Peel and cut potatoes into medium pieces and cook in a large saucepan of boiling water on stove until tender
Drain and add milk and butter and mash to a smooth mashed consistency
Add pie filling into an oven proof baking dish, spoon mash on top - bake 40-45min