Preheat oven to 350. Line baking sheets with parchment paper and file a pastry bag with a medium, straight tip.
For the cookies, whisk:
3/4 cup each all-purpose flour and unsweetened cocoa powder
1/2 tsp. table salt
2 sticks softened, unsalted butter
2 cups sifted powdered sugar
1/2 cup granulated sugar
6 egg whites
Cream the butter and both sugars with a mixer on medium speed until light and fluffy. Add egg whites a little at a time, beating to full incorporate. Mix in flour-cocoa mixture. Transfer batter to prepared pipping bag.
Pipe batter onto baking sheets in strips 3/4 inch wide and 2 inches long. Bake until crisp around the edges; 18-20 minutes; cool on pan.
For the filling:
1/4 cup heavy cream
1/2 tsp. mint extract
8 oz white bar chocolate, chopped
green food coloring
Microwave the cream and extract until boiling; pour over chocolate in a bowl. Let mixture stand 5 minutes, then stir until smooth. Add food coloring a drop at a time until desired color is reached; stir to blend.
To assemble, spread filling onto one cookie and top with another to form sandwiches. (Betcha you couldn’t have figured that one out for yourselves!)
Recipe from Cuisine At Home December 2011