In a medium bowl stir together flour and cocoa powder; set aside.
In a large bowl beat shortening and butter with an electric mixer on medium to high speed for 30 seconds. Add sugar and baking powder. Beat until combined, scraping side of bowl occasionally. Beat in eggs, liqueur, and vanilla until combined. Beat in as much of the flour mixture as you can with the mixer. Using a wooden spoon, stir in any remaining flour mixture. Stir in chocolate pieces and nuts.
Drop dough by a rounded teaspoon 2 inches apart onto an ungreased cookie sheet. Flatten each mound of dough with the bottom of a glass dipped in additional sugar.
Bake in a 375 degrees oven for 7 to 9 minutes or until edges are firm. Transfer cookies to a wire rack; cool. Makes about 72 cookies.