Beat butter in a large mixing bowl at medium speed of an electric mixer; gradually add sugar, beating well. Add bourbon and pecans; mix well.
Shape mixture into 1-inch balls, and place on waxed paper lined baking sheets. Chill at least 30 minutes.
Place chocolate morsels in top of a double boiler. Cook over simmering water, stirring constantly, until chocolate melts. Remove from heat, leaving chocolate over hot water. Using 2 forks, quickly dip chilled balls, one at a time, into melted chocolate. (To maintain coating consistency, add a small amount of warm milk to chocolate, if necessary.) Return bonbons to waxed paper-lined baking sheets, and chill until firm. Store in airtight containers in refrigerator.