Preheat oven to 375F.
Roasted Squash: In large roasting pan place squash, onions, chiles, salt and pepper. Drizzle with olive oil. Cover; roast at 375° F for 1 1/2 to 2 hours, until tender. Scoop squash pulp from skin.
Gratin: Combine 3 cups roasted squash with roasted onions and chiles in 2 quart gratin dish. Layer with cheese. In skillet, sauté bread crumbs in olive oil, stirring occasionally, until browned. Sprinkle over cheese slices; top with pumpkin seed nuts. Bake at 375° F for 15 to 20 minutes or until heated through.