Bake uncovered 40 to 45 minutes. Meanwhile, toast waffles until golden brown. Cool slightly, about 2 minutes. Cut waffles into 3/4-inch cubes; set aside. Spray 1-quart casserole with cooking spray (or use 9x5-inch nonstick loaf pan; do not spray). In 10-inch nonstick skillet, melt butter over medium heat. Add onion; cook and stir about 2 minutes or until tender. Stir in waffle pieces and broth, breaking up waffle pieces slightly to moisten. Sprinkle with poultry seasoning and sage. Remove from heat; cool about 5 minutes. Stir in egg white and spinach. Spoon stuffing into casserole. Sprinkle pecans over top.