Sift together flour, cocoa powder, baking soda and salt into a medium-size bowl; set aside. In a large bowl, beat together sugar and butter until smooth and creamy. Beat in egg, then vanilla and mint extract.
Beat flour mixture into butter mixture. Divide dough in half; shape each into a log about 1-1/2 inches in diameter. Cover with plastic wrap; refrigerate 3 to 4 hours.
Heat oven 375 degrees F. Cut each log into 1/16-inch-thick slices; place on ungreased baking sheets
Bake in heated oven to 375 degrees F. oven 8 to 10 minutes or until almost firm. Remove cookies to a wire rack to cool.
Prepare filling: Beat together confectioners' sugar, butter, milk and mint extract in a medium-size bowl until a good spreading consistency. Divide filling in half; tint half with red food coloring, and other half with green food coloring.
Spread flat side of one-quarter of the cookies with red filling and one-quarter with green filling. Top each with a plain cookie. Chill until set.
Nutritional Information: (per cookie)
67 Calories; 1 g Protein; 5 g Fat; 6 g Carbohydrate;
1 mg Sodium; 9 mg Cholesterol
