Mint Chocolate Sandwich Cookies

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 and shape each into a log about 1-1/2 inches in diameter. Cover with plastic wrap and refrigerate for 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 oven preheated to 375 degrees F for 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.