2 cups sifted all-purpose flour 2 cups granulated sugar 1 teaspoon baking soda 1 cup (2 sticks) unsalted butter (not margarine) 1 cup water ¼ cup unsweetened cocoa powder 2 large eggs, beaten ½ cup low-fat buttermilk 1 tablespoon vanilla extract
For the frosting ¼ cup (1/2 stick) butter (not margarine) ¼ cup unsweetened cocoa powder 6 tablespoons low-fat buttermilk 1 pound sifted confectioner’s sugar (4 ½ cups) 2 teaspoons vanilla extract 1 cup chopped walnuts
Preheat the oven to 400 degrees F and butter a 15 ½" X 10 ½" - baking pan. In a large bowl, sift the flour, sugar and baking soda.
In a small saucepan, bring the butter, water and cocoa to a boil over moderate heat. Pour over the flour mixture, whisking until smooth. Blend in the eggs, buttermilk and vanilla. Pour into the pan. Bake for 15 minutes or just until the top springs back when lightly touched.
Meanwhile, make the frosting In a medium-size saucepan, over moderate heat, stir the butter, cocoa and buttermilk for 4 minutes or just until the mixture begins to bubble. Remove from the heat and stir in the remaining ingredients. When the brownies come out of the oven, immediately spread the frosting on top. Cool in the pan on a rack for at least 1 hour, then cut into 2-inch bars.
