Place sauté pan back on stovetop, add butter and melt over low-medium heat. Add celery, leeks and scallions and sauté for a few minutes or until softened but not browned. Add the chopped apple, parsley, sage, thyme, salt and pepper and sauté for about 1 minute more to combine. Turn heat up, add the white wine and sauté for about 1 minute more. Scrape mixture over bread cubes and fold well to combine.
Add enough stock to create a slightly moist mixture. Scrape into prepared dish and cover with aluminum foil.