In a small saucepan heat and stir chocolate and shortening over very low heat till chocolate begins to melt. Remove from heat. Add coffee. Stir till smooth. Cool.
Beat eggs and sugar with an electric mixer on medium to high speed till light and lemon colored (3 to 4 minutes). Beat in chocolate mixture and vanilla. On low speed, beat in pecans, flour, cinnamon, baking powder, and salt till combined.
Spray cookie sheets with nonstick coating. Drop teaspoons of dough 2 inches apart on cookie sheets. Place a pecan half on top each cookie, if desired. Bake in a 350 degree oven for 8 to 10 minutes or till just set on surface (do not overbake). Cool for 1 to 2 minutes; transfer to racks. Cool completely. If desired, sprinkle with powdered sugar.