In a large mixing bowl with an electric mixer on medium to medium high speed, beat butter for 30 seconds. Add sugar and baking powder and beat till combined. Beat in egg, mint extract, 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 refrigerate about 1 hour or till easy to handle.
Roll one half of dough between two (2) sheets of waxed paper into an 8 x 7-inch rectangle. Peel off top sheet of waxed paper. Sprinkle half of the crushed cookies evenly over dough to within 1/4 inch of all sides. Roll up, jelly-roll style, starting from one short side, removing bottom sheet of waxed paper as you roll. Pinch to seal. Repeat with remaining dough and crushed cookies. Wrap rolls in waxed paper or plastic wrap. Refrigerate about 4 hours or until firm.
Preheat oven to 375 degrees F.
When ready to bake, 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 sheets.
Bake approximately 8 to 9 minutes or till edges are firm. Remove from oven and let cool on cookie sheet for 1 minute. Remove and cool completely on a wire cooling rack. Repeat with remaining roll of dough.
In a saucepan, melt the chocolate chips and vegetable shortening over low heat. Remove from heat and drizzle over top of the baked and cooled cookies. 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.)
After Dinner Mint Cookies Recipe: https://whatscookingamerica.net/Cookie/AfterDinnerMintCookies.htm