How to Make It
Preheat the oven to 425°. Grease a 4-quart baking dish. Spread the bread on a baking sheet and toast for about 10 minutes, until golden and crisp.
In a large nonstick skillet, heat 1 tablespoon of the olive oil. Add the sausage and cook over moderate heat, stirring occasionally, until browned, about 5 minutes. Add the leeks and garlic and cook until softened, about 5 minutes. Scrape the sausage mixture into a large bowl; wipe out the skillet.
In the skillet, heat 2 tablespoons of the oil. Add half of the mushrooms, season with salt and pepper and cook over moderately high heat, stirring occasionally, until deep golden, about 8 minutes. Transfer to the large bowl. Repeat with the remaining oil and mushrooms, seasoning with salt and pepper and transferring to the bowl. Add the bread, broth, eggs and the 1/2 cup of chopped parsley and mix well. Let stand for 5 minutes, allowing the bread to absorb the liquid.
Scrape the stuffing into the prepared dish and drizzle with the 3 tablespoons of melted butter. Cover and bake for 30 minutes. Uncover and bake for 30 minutes longer, until golden and cooked through. Serve the stuffing hot, garnished with parsley.