Preheat oven to 400°.
Steam pumpkin, covered, for 10 minutes or until tender. Drain.
Place the pumpkin, pear, and next 7 ingredients (pear through pepper) in a large bowl, tossing gently to coat. Spoon into an 11 x 7-inch baking dish coated with cooking spray. Cover and bake at 400° for 20 minutes.
Place bread in a food processor; pulse 10 times or until coarse crumbs form to measure 1 cup. Combine breadcrumbs, cheese, and butter. Uncover gratin; top with breadcrumb mixture. Bake an additional 10 minutes or until golden brown.