In a small bowl soften 1/2 a stick of butter.  Add the bourbon & whisk.  Add the powdered sugar and whisk again.  Last, use a wooden spoon to fold in some chopped pecans (optional). Dust your hands with powdered sugar to prevent sticking and begin to roll the filling into little balls.  Continue making balls until you have used all the filling.  Lay them on a (greased) bakers sheet as you go.  Transfer the cream centers into the refrigerate to harden (1-2 hours). Melt the chocolate.  Using a toothpick, dip each cream center into the melted chocolate to coat. Move the bourbon balls to a sheet of wax (or parchment) paper to set.  Place a pecan half on top of the candy while the chocolate is still soft. Store in the refrigerator up to 2 weeks.