Spread the ciabatta cubes out on baking sheets and leave at room temperature to dry out for 24 hours before making the stuffing.
Preheat the oven to 375 degrees F. Butter a 9-by-13-inch baking dish and set aside.
Heat the broth in a small saucepan over medium-low heat.
Add the bacon to a large skillet and place over medium heat. Cook, stirring often, until almost browned and crispy, about 5 minutes. Stir in the carrots, celery and red onion and season with the salt. Continue to cook, stirring often, until the vegetables are beginning to soften and the bacon is crispy, an additional 4 minutes. Remove from the heat and stir in the chestnuts, rosemary and radicchio.
Place the bread cubes in a large bowl. Add the vegetable mixture to the bowl along with the olive oil and 1 cup of the Parmesan cheese. Toss well to combine. Add the broth and toss again until the bread mixture is entirely and evenly moistened.
Pour the mixture into the prepared dish and top with the remaining 1/2 cup Parmesan. Dot with the butter and cover with foil. Bake, covered, for 30 minutes. Uncover and cook until browned and crispy on top and warm all the way through, an additional 20 minutes.