Soften the cream cheese. Cut the ounces cream cheese into at least 4 pieces and let it soften at room temperature while you prepare the soup.
Cook the bacon. Add the bacon to a large dutch oven and heat to medium high. Cook until crisp. Remove from pan with a slotted spoon and set aside.
Saute the onions. Reduce the heat to medium and add the butter to the pan. Add the onion and saute for 2 minutes. Add the celery salt and pepper and saute for 30 seconds.
Make the roux. Add the flour and whisk for 30 seconds. Slowly adding the milk and whisking until smooth.
Cook the potatoes. Add the chicken broth and potatoes. Bring to a boil over medium-high heat. Cover, reduce heat and simmer for 20 mintues or until potatoes are very tender.
Finish the soup. Once the potatoes are tender, use a potato masher to slightly mash them while still in the pot. Stir in the cream cheese and ¼ cup of the grated cheddar cheese. Cook for 5 minutes or until the cheeses are melted.
Serve. Ladle the soup into bowls. Top with the cooked bacon, cheedar cheese and green onions.