Melt the chocolate chips and combine with the brown sugar and vegetable oil. Add the eggs one at a time and beat well. Stir in the vanilla.
Combine the flour, baking powder and salt. Add flour mixture to the chocolate mixture. Stir in the chopped walnuts. Chill dough for a few hours.
Preheat oven to 350 degrees F (175 degrees C). Grease baking sheets.
Drop teaspoonfuls of dough in confectioners' sugar and roll to coat. Place cookies on the prepared baking sheets. Bake at 350 degrees F (175 degrees C) for 10 to 12 minutes. Let cookies cool on racks.