Wash and scrub potatoes, pat dry. Rub potatoes with butter and place in baking pan, bake at 350 for 1 hour and 15 minutes or until the done.
Remove from oven and cool slightly. When the potatoes have cooled enough to touch, peel 4 of the potatoes, we will need the skin on the 5th potato.
While potatoes are cooling, add fennel seeds to milk and half and half, and scald the milk. Scalding is heating milk at a moderated temperature just until a boiling point but not boiling and quickly remove from heat.
Scalding will keep the mixture from separating. Let milk cool slightly with fennel seeds in the mixture. When potatoes or cool enough to work with carefully cut 4 in half and place in a food processor.
Potatoes should measure out to 1 1/2 - 2 cups cooked potato. Dice the 5th potato and set aside, leave the potato skins on this potato. To the cooked potato add sour cream, chives, salt, pepper, celery salt and 1/2 cup plus 1 tablespoon shredded cheddar cheese.
Strain the fennel seeds from warm milk and discard seeds, pour milk mixture into food processor and processes 1 1/2 - 2 minutes until smooth.
Place mixture into a saucepan add butter and diced potato stir frequently and simmer on very low setting for about 15 - 20 minutes. When ready to serve ladle into individual bowls and garnish with cheddar cheese, bacon, and green diced onion.