Thanksgiving Potato Filling

15 med. potatoes, peeled & boiled
2 med. onions
1 stalk celery
1/2 lb. butter (1 cup)
1 tsp. garlic powder
1 tsp. oregano
1/2 tsp. celery salt
1 tsp. onion powder
1 tsp. salt
1/4 tsp. pepper
3 c. milk
12 oz. soft bread cubes
3 eggs

Chop onion and celery, brown in 3/8 pound of butter. Mash potatoes, mix with remainder of butter, milk and eggs. Add spices and bread cubes and browned onions and celery. Put into two 2 quart casseroles. Cover and bake at 350 degrees for 45 minutes. Uncover and bake another 20 minutes or until top browns.