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.
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 the stuffing 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.