Celery-Herb Stuffing

INGREDIENTS

• 7 tablespoons unsalted butter, plus more for dish and baking
• 1 loaf rustic white or Italian bread, crusts removed, cut into 1/2-inch cubes (about 9 1/2 cups)
• 1 celery root, (about 1 1/2 pounds), peeled and cut into 1/2-inch dice
• Coarse salt and freshly ground pepper
• 2 tablespoons extra-virgin olive oil
• 3 celery stalks, thinly sliced on the diagonal
• 2 medium onions, halved lengthwise and thinly sliced in half-moons
• 2 cloves garlic, finely chopped
• 1/2 cup extra-dry vermouth
• 1/2 to 1 3/4 cups homemade or low-sodium store-bought chicken stock
• 1/2 teaspoon poultry seasoning (such as Bell's)
• 3 tablespoons coarsely chopped fresh flat-leaf parsley
• 3 1/2 teaspoons finely chopped fresh sage
• 2 teaspoons finely chopped fresh thyme
• 2 teaspoons finely chopped fresh rosemary
• 3 to 4 large eggs, lightly beaten