1Heat oven to 350°F. Grease bottom of 8-inch square pan.
2In 2-quart saucepan, heat granulated sugar and 1/2 cup butter, stirring frequently, just until butter is melted. Cool 10 minutes. Beat in salt, 1 teaspoon vanilla and the eggs with spoon. Stir in flour blend and 1/2 cup baking cocoa; stir in pecans. Spread batter in pan.
3Bake 25 to 30 minutes or until brownies begin to pull away from edge of pan. Immediately sprinkle with marshmallows. Set oven control to broil. Broil about 2 minutes or until marshmallows are puffed and beginning to brown.
4Meanwhile, heat 1/4 cup butter, the milk and 3 tablespoons baking cocoa in 2-quart saucepan over medium heat until butter is melted and mixture is smooth. Stir in 1/2 teaspoon vanilla and the powdered sugar until thick yet pourable. Pour over marshmallow layer, spreading with spatula to cover marshmallows. Cool completely on cooling rack, about 2 hours. Cut into 4 rows by 4 rows.