Heat oil over medium heat. Add diced celery & onions and cook until softened, about 5 minutes (be careful not to brown). Cool completely. Stir in poultry seasoning, pepper and salt.
Place bread cubes in a large bowl. (Note: If you are making your own bread crumbs, it is essential they are dry before making the stuffing.
There are two ways I dry bread for stuffing:
1. Cut your bread into cubes and leave it on the counter uncovered at least 24 hours (stirring occasionally).
2. Dry bread crumbs in the oven: Preheat oven to 300 degrees. Lay fresh bread cubes in a single layer and cook 25 minutes stirring half way or until dried. Ensure your bread doesn’t toast or brown.
Add celery and onion mixture to the bowl with the breadcrumbs. Add fresh herbs, pecans, or cranberries if using.
Add chicken broth a little bit at a time just to moisten and gently stir. Only use enough broth to moisten the bread, not overly saturate it, otherwise you will end up with soggy dressing. (Note: if using bread cubes you have dried yourself at home you will need closer to 2 cups of broth. If using dried store bought bread cubes/crumbs, you will need closer to 3 cups broth). Stir in eggs. Cover and refrigerate overnight if making ahead of time.
Spray a 5-6 qt slow cooker well. Place stuffing in the slow cooker and 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.