10 tablespoons unsalted butter, plus more for the baking dish
4 stalks celery, chopped
2 leeks, halved and thinly sliced
2 Gala apples, cut into 1/2-inch cubes
1 12-ounce jar peeled cooked chestnuts, crumbled (about 1 1/2 cups)
1 tablespoon chopped fresh thyme
1 tablespoon chopped fresh sage
Kosher salt and freshly ground pepper
3 cups low-sodium chicken broth
2 large eggs
1/4 cup chopped fresh parsley
16 cups 1/2-inch stale brioche cubes (about 1 1/2 pounds)
1 cup dried cherries