Put the bread cubes on a wire rack and let them dry completely overnight.
Adjust an oven rack to a lower-middle position and heat the oven to 375°F. Put the bread cubes in a large bowl. Lightly grease a 9x13-inch baking dish with a little oil or cooking spray.
In a 12-inch skillet over medium heat, cook the bacon until crisp, 15 to 20 min. Transfer the bacon with a slotted spoon to a plate lined with paper towels. Add the onions and celery to the bacon fat in the skillet and cook until softened, 8 to 10 min.
Transfer the onions and celery to the bowl of bread cubes. Add the bacon, chestnuts, prunes, parsley, sage, thyme, and pepper. Whisk the chicken broth and eggs together and add them to the dressing mixture; toss to combine. If there’s liquid in the bottom of the bowl, let the dressing sit, tossing frequently, until the liquid is absorbed, 3 to 5 min.
Spread the mixture evenly in the baking dish, cover with foil, and bake until completely heated through, about 30 min. Remove the foil and continue to bake until the dressing is lightly golden brown and crisp on top, about another 20 min.
Up to five days ahead: Prepare dried bread cubes; store in a zip-top bag. The night before: You can prep the dressing ingredients, including sautéing the onions, celery, and bacon. (Before assembling, be sure to reheat the vegetables to liquefy the bacon fat.) Assemble the dressing no more than an hour before baking.