Banana-Walnut Scones
["3 c. all-purpose flour", "1/2 c. packed brown sugar", "2 tsp. baking powder", "1/2 tsp. salt", "1/4 tsp. baking soda", "3 Tbsp. chilled margarine or butter", "1/4 c. low-fat buttermilk", "1 tsp. vanilla extract", "1 lg. egg or 2 lg. egg whites", "1 c. mashed, ripe banana (about 2 medium bananas)", "Cooking spray", "1/3 c. walnuts, coarsely chopped", "1 Tbsp. brown sugar"]
["Preheat oven to 400."]
["all-purpose", "brown sugar", "baking powder", "salt", "baking soda", "margarine", "low-fat buttermilk", "vanilla extract", "egg", "banana", "Cooking spray", "walnuts", "brown sugar"]