1. Preheat oven to 350F. Grease 15 1/2"x10 1/2" jelly-roll pan. In heavy 2-quart saucepan over low heat, heat unsweetened chocolate squares until melted and smooth, stirring frequently. 2. In large bowl, with mixer at low speed, beat sugar, corn syrup, vanilla and 1 cup butter or margarine just until blended. Increase speed to high; beat until light and fluffy. Reduce speed to low; add flour, salt, and eggs; beat until well mixed, constantly scraping bowl with rubber spatula. Increase speed to high; beat 2 minutes. At low speed, beat in melted chocolate until blended. With spoon, stir in walnuts. Evenly spread batter in pan. Bake 40 to 45 minutes until toothpick inserted in center comes out clean. Cool brownies in pan on wire rack. 3.When brownies are cool, prepare mint butter-cream frosting: In large bowl, with mixer at low speed, beat confectionners' sugar, milk, peppermint extract, and 6 tablespoons butter until smooth. Stir in enough green food coloring to tint a pretty green. Evenly spread frosting over cooled brownies. Refrigerate while preparing Chocolate Glaze. 4. Prepare Chocolate Glaze; spread over frosting to completely cover top. Refrigerate until glaze is set, about 1 hour. Cut brownies lengthwise into 3 strips; cut each strip crosswise into 15 bars. Makes 45. About 245 calories each.
Chocolate Glaze: In heavy 2-quart saucepan over low heat, heat 3 squares unsweetened chocolate, 1 square semisweet chocolate, 4 tablespoons butter and 2 teaspoons dark corn syrup until chocolate melts and mixture is smooth, stirring frequently. Remove saucepan from heat; stir frequently until glaze cools slightly.