Preheat oven to 400 degrees F (200 degrees C). In the microwave or over a double boiler, melt chocolate stirring frequently until smooth. Remove from heat.
In a medium bowl, cream together the sugar and margarine until smooth. beat in the egg, melted chocolate and vanilla until well blended. Combine the flour, baking soda and salt; stir into the chocolate mixture alternately with the milk. Drop batter by heaping teaspoonfuls onto cookie sheets, about 1 inch apart.
Bake 8 to 10 minutes until cookies are puffy and slightly cracked on top. Let cool on wire racks.
Top cookies with Chocolate Butter-Cream Frosting (see recipe) and garnish with pecans.