Heat butter over medium heat until melted.Add celery & onions and cook until softened (do not brown). Cool completely.
Stir in poultry seasoning, black pepper and salt. Cool completely.
Stir in eggs.
Place bread cubes in a large bowl. Add cooled celery and onion mixture, parsley and fresh herbs if using.Cover and refrigerate overnight if making ahead of time.
Grease a 5-6 qt slow cooker well.
Place bread cuts in the slow cooker.
Pour the celery, butter mixture over the top.
Add chicken broth a little bit at a time just to moisten and gently stir. You may not need all of the broth
Turn onto high for 30 minutes. Reduce temperature to low and cook an additional 3-4 hours or until hot and cooked through. If stuffing is done before your meal is ready it can remain on warm.
Notes - check on it regularly and stir if needed - if stuffing begins to dry out add more broth. You can use drippings from your turkey if making on Thanksgiving for even more flavor. Top with more fresh parsley before serving.