Espresso Chocolate Chip Shortbread

You simply just have to make this.  It is so good and so easy.  A perfect little treat to have with coffee or to give as a gift.  Here's the skinny...
1 Tablespoon espresso shot or extra dark coffee, room temperature
1 cup butter, softened
2/3 cup confectioners sugar
1/2 teaspoon vanilla
1/8 teaspoon espresso grounds (or dark coffee grounds)
2 cups flour
1/2 cup mini semi sweet chocolate chips
Cream butter and confectioners sugar for a few minutes until smooth.  Beat in vanilla, espresso shot, and espresso grounds.  On low speed beat in flour just until it is incorporated.  Using a spoon, fold in the chocolate chips.  Transfer dough to a gallon size Zip-loc bag.  Roll dough out inside of bag until dough is flat (about 1/4 inch) and fills up the entire bag.  Make sure to fix the plastic as you roll so there are no crease marks in your dough.  Zip the bag up and place on cookie sheet.  Refrigerate for at least 2 hours.
Preheat oven to 325 degrees.  Remove dough from fridge & using scissors cut off the plastic bag (be careful not to make marks in your dough).  Using a pizza cutter or knife cut dough into 1 1/2 inch squares.  Place squared onto ungreased cooking sheet.  Bake for 18-20 minutes.  Cool and enjoy!  (makes about 36 short breads)