In a bowl combine butter and sugar on medium-high speed until light and fluffy, about 2 minutes.

Beat in the flour, sweetened condensed milk and vanilla until incorporated, beating well after each addition.

Stir in chocolate chips and walnuts.

Cover with plastic wrap and refrigerate for about 1 hour, or until firm enough to handle.

Shape mixture into 1 inch balls by rolling a spoonful in the palm of your hand, since the dough is sticky, roll your fingers into flour. This will make it easier to roll.

Place on waxed paper-lined baking sheets. Loosely cover and refrigerate for 15-20 minutes or until firm again.

In a bowl melt dark chocolate candy coating.

Dip the cookie dough balls into the chocolate and place on parchment paper.

Let the truffles sit until hard, about 15 minutes.

Once set, remelt remaining candy coating.

Place in a small baggie and cut a small hole in one corner.

Carefully drizzle chocolate over truffles.

Store in the refrigerator and serve cold. These can also be frozen for longer storage.