Mix all ingredients in small bowl; set aside. Sift first 5 ingredients into medium bowl. Whisk 2 cups milk, egg, egg white and butter in large bowl to blend. Whisk in dry ingredients. Thin with remaining 1/4 cup milk if too thick. Mix in walnuts. Preheat oven to 200°F. Spray non-stick griddle or skillet with oil spray. Heat over medium heat. Working in batches, pour batter onto griddle by scant 1/4 cupfuls. Cook until bubbles appear and bottoms of griddle cakes are golden, about 3 minutes. Turn and cook until bottoms are golden, about 2 minutes. Transfer to baking sheet. Keep warm in oven. Serve with orange butter and maple syrup.