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