Preheat oven to 350F. Beat eggs lightly with wire whisk in large bowl. Add sugar. Stir well. Combine flour and cocoa, gradually stirring into egg mixture, Stir in 1 cup butter and flavorings. Pour into a 15 x 10 x 1 inch greased jelly roll pan. Bake at 350F for 15-18 minutes. Check with wooden pick. Cool in pan on wire rack. Leave in pan. While cooling make Mint Cream Frosting. Spread over brownie layer.
Beat butter at medium speed with electric mixer. Gradually add sifted powdered sugar, beating after each addition. Add milk. beat until mixture is spreading consistency, Stir in peppermint flavoring and food coloring (about 5 drops for bright color). Freeze for 15 minutes. For third layer make, Chocolate Topping.
Break up chocolate squares and margarine together in glass cup or bowl. Melt in microwave, stirring until well blended OR melt in a double boiler, stirring until blended. While hot, spread over frosting with a pastry brush. Refrigerate until firm. When cool, cover tightly with plastic. Store in refrigerator. (It freezes well, also), Leave in jelly roll pan unless freezing.
Cajun Country -- New Iberia, Louisiana