Cut squash into large pieces. Drop into a large sauce pan with enough boiling water to cover. Return to a boil, reduce heat and cook until tender. Drain in colander and mash. Combine eggs, bread crumbs. butter, sugar, onion, salt and pepper. Turn into a casserole pan that has been lightly sprayed with Pam. Cover with a light layer of bread crumbs. Bake at 350 for 20-25 minutes or until lightly browned.