Spread bread cubes in a single layer on two large sheet pans and let dry for a few hours or overnight. Adjust oven racks to lower- and upper-middle positions. Heat oven to 400 degrees. Bake bread until golden, 12 to 15 minutes. Reduce heat to 350 degrees.
Meanwhile, heat butter in a large skillet over medium-high heat. Add onions and celery; saute until soft, 8 to 10 minutes. In a large bowl, mix bread, vegetables and remaining ingredients. Turn into a greased 3-quart baking dish. Cover with foil and bake until steamy, 30 minutes. Remove foil; bake until crusty, 10 minutes longer. Serve immediately.
