Line a 8" square pan with foil; spray with nonstick cooking spray. Place chocolate, marshmallows and espresso coffee powder in a large bowl. In a heavy large saucepan, stir together sugar, evaporated milk and butter. Bring to a rolling boil over medium heat, stirring occasionally; boil 6 minutes.
Now pour hot milk mixture over the chocolate mixture. Stir gently until combined with a clean spoon. Let stand 3-4 minutes until marshmallows are soft; stir until smooth. Stir in the pecans. Pour into the square pan. Refrigerate 3-4 hours or until firm. Cover tightly and store in the fridge up to 3 weeks.
To toast the pecan halves, place on a baking sheet; bake at 350*F. for 6-8 minutes or until slightly darker in color. Cool and enjoy!