Heat oven to 350°F. Grease and flour 9-inch square pan. In small bowl, combine all topping ingredients; blend well. Set aside.
In medium saucepan, melt 4 oz. chocolate and 3 tablespoons margarine over low heat, stirring constantly until smooth. Remove from heat; cool 15 minutes. Add 1/2 cup sugar and vanilla; blend well. Beat in 2 eggs 1 at a time, blending well after each addition. Add flour, baking powder and salt; stir just until blended. Pour into greased and floured pan. Pour topping over batter.
Bake at 350°F. for 40 to 50 minutes or until toothpick inserted in center comes out clean. Cool completely.
In small saucepan, melt glaze ingredients until smooth, stirring constantly. Drizzle over brownies. Refrigerate at least 4 hours. Cut into bars. Store in refrigerator.