Beat butter or maragrine in a large mixing bowl with an electric mixer on medium to high speed for 30 seconds. Add sugar and baking powder and beat till combined. Beat in egg, mint extraxt, and enough food coloring to tint light to medium green. Beat in as much of the flour as you can with the mixer. Stir in any remaining flour with a wooden spoon. Divide dough in half. Cover and chill about 1 hour or till easy to handle.
Roll one half of dough between two sheets of waxed paper into an 8x7 inch rectangle. Peel off top sheet of waxed paper. Sprinkle half of crushed cookies evenly over dough to within 1/4 inch of allsides. Roll up, jelly-roll style, starting from one short side, removing bottom sheet of waxed paper as you roll. Pinch to seael. Repeat with remaining dough and crushed cookies. Wrap rolls in waxed paper or clear plastic wrap. Chill about 4 hours or until firm.
Remove one roll of dough from the refrigerator. Unwrap and reshape slightly if necessary. Cut dough into 1/4-inch slices. Place 2 inches apart on an ungreased cookie sheet.
Bake in 375 degree oven for 8 to 9 minutes or till edges are firm. Cool on cookie sheet for 1 minute. Remove and cool completely on a wire rack. Repeat with remaining roll of dough. If desired, melt together in a saucepan, the chocolate and shortening over low heat. Drizzle over cookies.
Hint: When dough has been rolled, chill upright in a glass to avoid a long flat bottom.
Hint: To drizzle chocolate: Put in a small plastic bag and make a Small cut in one of the bottom corners of the bag. Use like a pastry bag.
Per serving: 70 Calories; 3g Fat (43% calories from fat); 1g Protein; 9g Carbohydrate; 11mg Cholesterol; 36mg Sodium