Combine squash onion and water in saucepan Bring to a boil reduce heat and simmer 5 to 10 minutes or until squash is tender Drain and mash Combine squash cheese pecans mayonnaise pepper egg sugar and salt stirring well Spoon into lightly greased 2-quart casserole Combine cracker crumbs and butter stirring well Sprinkle over casserole Bake at 350 for 40 minutes or until thoroughly heated Yield 6 to 8 servings