Crisping the prosciutto and toasting the nuts adds a powerful punch of flavor to the stuffing without going overboard on fat. Packaged chopped hazelnuts are available in most major supermarkets.
Preheat the oven to 350 degrees. Coat a 9-by-13-inch baking dish with cooking spray.
Heat 1 teaspoon of the oil in a large, nonstick skillet over medium heat. Add the prosciutto and cook, stirring, until crispy, about 5 minutes. Drain on a paper towel.
Wipe out the pan and heat the remaining oil over medium-high heat. Add the onions, fennel, and shallots and cook, stirring, until softened and beginning to brown, 6-8 minutes.
Add the sage, thyme, and rosemary and cook, stirring, for 1 more minute. Transfer everything to a large bowl and gently stir in the bread, pears, parsley, hazelnuts, and prosciutto. Add the broth and toss to combine. Season with the salt and pepper, to taste. Spoon the stuffing into the baking dish and cover with foil. Bake for 40 minutes, then remove the foil and bake until the top is beginning to crisp, 25-30 more minutes.