Although I have never before put egg into filling, it worked quite well. Due to an allergy, I made this without the onion and it was still quite good. I used a large egg, panel bread crumbs and Herbs de Provence (instead of the poultry seasoning). I baked a 350 for 20 - 30 minutes.
10 medium potatoes
2 tbl butter
1 cup bread crumbs (about 3 slices - not too dry)
1 large onion, chopped fine
4 stalks celery, chopped fine
A few sprigs of parsley, chopped fine
1 tbl light brown sugar
1 tsp salt
2 tsp poultry seasoning
Cook the potatoes unto soft. Add butter and eggs and mash. Add other ingredients and mix thoroughly. Put in a buttered dish and brown in a moderate oven. Can also be used to stuff a bird.