Baked Onions With Black Walnut And Sausage Stuffing

Ingredients

• 6 medium red onions
• 2 tablespoons extra-virgin olive oil
• ½ teaspoon coarse salt
• ¼ teaspoon ground black pepper
• 8 ounces sweet Italian sausage
• 2 celery stalks, finely diced
• 2 cloves garlic, minced
• 1 pear, cored and finely diced
• ¾ cup black walnuts, roughly chopped
• ¾ cup dried bread crumbs
• ¼ cup chopped parsley, plus more for garnish
• 1 tablespoon finely chopped fresh sage
• 2 eggs, lightly whisked
• 4 ounces grated Gruyère cheese, divided
• ¾ cup chicken broth