Preheat the oven to 400 degrees F. In a medium bowl, mix the first 8 ingredients and season with Old Bay, salt, and pepper. Transfer to a 2-quart baking dish and then smooth the top of the dip. Sprinkle it with the crushed saltines and scatter the butter slices over the top.
Bake until golden brown and bubbly, about 25 minutes. Garnish with the chives. Serve with the celery and saltine crackers.