Preheat oven to 350°F. Line a cookie sheet with parchment paper.
Using an electric mixer, cream together butter and sugars until light and fluffy.
Mix in egg and extra egg yolk along with vanilla extract.
In a small bowl, combine flour, baking soda, salt, and espresso powder.
Add flour mixture to sugar mixture and mix just until combined.
Stir in chocolate chips and grated dark chocolate.
Shape dough into one Tablespoon rounds and place evenly apart on cookie sheet.
Bake 13 minutes. Let cool on cookie sheet 5 minutes before removing to a wire rack. Store in an airtight container.
