Preheat oven to 350 degrees F. Grease two jumbo doughnut pans and set aside.
Place the bagel cubes on a baking sheet in an even layer and bake until golden brown and the bread pieces have dried out a bit, about 20 minutes. Give them a toss halfway for even browning. Remove from the oven and let cool.
Place a large skillet over medium-high heat. Add the bacon and cook, stirring often, until crispy. Using a slotted spoon, remove the bacon from the pan.
Drain all but 1 tablespoon of fat and then stir in the onion and celery. Cook until tender about 5 minutes. Season with salt and pepper.
In a large mixing bowl, whisk together the chicken stock, eggs, and 1/2 cup cream cheese until well combined. Add in the toasted bagel pieces, the cooked onions and celery, 3 tablespoons scallions and most of the bacon and mix until well combined and bread is well coated.
Divide the mixture evenly between the two pans and sprinkle with bagel seasoning. Bake until golden brown, 25 to 30 minutes. Remove from oven and let cool slightly.
Serve with a dollop of whipped cream cheese and garnish with remaining scallions and bacon.