Apple-Herb Cornbread Stuffing

6 cups cubed cornbread (about 1-inch cubes)
5 tablespoons unsalted butter
1 large sweet onion, chopped small
1 large or 2 small stalks celery, diced small
1 teaspoon chopped fresh thyme leaves
1/2 teaspoon table salt, plus more to taste
Freshly ground black pepper
1 large or 2 small firm, tart apples, such as Granny Smith, peeled, cored and diced small
1/4 cup roughly chopped flat-leaf parsley
3 sage leaves, minced
1/2 to 1 cup vegetable, chicken, or turkey stock or broth
1 large egg
 
Position rack in center of oven and heat to 350°F. Spread cornbread cubes in single layer on large rimmed baking sheet. Bake until pale golden, stirring occasionally, 10 to 15 minutes. Let cool in pan while you prepare the other ingredients.
 
Generously butter a 2-quart baking dish (a 9×5-inch loaf pan, 8- or 9-inch square dish, etc.) with 1 tablespoon butter. Melt remaining 4 tablespoons butter in large skillet over medium heat. Add onion, thyme, salt, and lots of freshly ground black pepper, and cook for 2 minutes, until becoming translucent. Add celery and cook for 2 more minutes. Add apple and sauté until a bit tender, 3 to 4 minutes more.
 
Place toasted cornbread cubes in a large mixing bowl. Scrape contents of skillet on top. Whisk egg and 1/2 cup stock together and pour over. Stir in parsley and sage. Spoon into prepared pan. If mixture looks a little dry, pour remaining 1/2 cup broth over it. (This is a good place to pause, if needed. Nothing bad comes of the stuffing absorbing the liquids for longer.) Bake for 30 to 40 minutes, until brown on top and no liquid appears if you insert a knife vertically into the center of the stuffing pan and turn it slightly. Serve immediately, or reheat as needed.
 
From Smitten Kitchen blog, with some changes