1. Heat oven to 375°F. Unwrap and coarsely chop chocolate bars; set aside.
2. Beat butter, brown sugar and granulated sugar in large bowl until well blended. Add egg, milk and vanilla; beat well. Stir together flour, baking soda and salt; gradually beat into butter mixture. With wooden spoon work chocolate bar pieces, coconut and walnuts into mixture. (Dough will be stiff.) Press mixture in ungreased 13x9x2-inch baking pan.
3. Bake 20 to 22 minutes or until edges are golden brown. (Do not overbake.) Cool completely in pan on wire rack. Drizzle VANILLA DRIZZLE over surface; allow to set. Cut into bars. Makes about 24 bars.
VANILLA DRIZZLE: Combine 1/2 cup powdered sugar and 2 teaspoons milk in small bowl. Add additional milk, 1/2 teaspoon at a time, until of desired consistency.