Mix together the melted chocolate, white sugar, oil and vanilla in a large bowl.
Stir in the eggs one at a time, incorporating each thoroughly before adding the next.
Stir in flour, baking powder and salt.
Cover and refrigerate for at least 3 hours.
Heat oven to 350°F. Line baking sheets with parchment paper.
Scoop out tablespoon-size amounts of dough, rolling each into a ball.
Drop each cookie dough ball into the powdered sugar, rolling it around to ensure it is well-coated. Place 3 inches apart on the baking sheets; these cookies are spread out.
Bake the cookies for 11-12 minutes or until the edges appear set and the centers still look soft. Another way to tell is that almost no imprint remains on the cookie top when touched lightly in the middle - watch them fairly carefully! These can overbake easily!
Cool the cookies for 5 minutes on the baking sheet, and then transfer to a cooling rack to cool completely.