Beat the butter, brown sugar and vanilla extract until combined. Slowly mix in the flour until just combined. Using a wooden spoon, stir in the miniature chocolate pieces.
Shape the dough into 3/4"-1" (2cm-2.5cm)balls and place on the 1st baking sheet. Freeze for 30 minutes or until firm.
While the cookie dough is in the freezer, use a clean and dry saucepan and heat the chopped chocolate, candy coating and shortening over LOW heat. Stir until chocolate is melted and smooth. Remove from the heat.
Use 2 forks and roll/dip the ball, one at a time, in the chocolate mixture. Allow the excess chocolate to drip back into the saucepan before placing on the 2nd lined baking sheet. Decorate with sprinkles and chill for 20-30 minutes. Lightly drizzle the truffles with the remaining melted chocolate mixture.
Store in air tight container and refrigerate.
Notes
Make sure all the tools used for melting the chocolate are dry. Even a tiny water droplet will make the chocolate seized (harden) when it is melting. You can also use the double boiler or microwave method to melt the chocolate.