Chocolate Chip Cookie Cake
["1 (12 oz.) pkg. semi-sweet chocolate chips", "1 c. toasted walnuts, chopped", "3 c. all-purpose flour", "1 tsp. baking powder", "2 tsp. baking soda", "3/4 tsp. salt", "1 c. (2 sticks) unsalted butter (room temperature)", "1 1/2 c. firmly packed brown sugar", "4 eggs (room temperature)", "2 1/2 tsp. vanilla", "1 c. buttermilk", "powdered sugar (optional)"]
["Position rack in center of oven and preheat oven to 350\u00b0. Generously grease a 9 to 10-cup fluted tube pan; dust with sugar. Mix chocolate chips, walnuts and 2 tablespoons of flour in medium bowl.", "Sift remaining flour with baking soda, baking powder and salt.", "With electric mixer, cream butter until light.", "Add brown sugar and beat until fluffy.", "Beat in eggs, one at a time.", "Add vanilla.", "Mix dry ingredients alternately with buttermilk, beginning and ending with dry ingredients.", "Fold chocolate/walnut mixture into batter.", "Place in prepared pan.", "Bake about 55 minutes.", "Cool in pan 15 minutes.", "Invert onto rack.", "Dust with powdered sugar.", "Makes 8 to 10 servings."]
["semi-sweet chocolate chips", "walnuts", "all-purpose", "baking powder", "baking soda", "salt", "unsalted butter", "brown sugar", "eggs", "vanilla", "buttermilk", "powdered sugar"]