In a large bowl, beat together sugar, vegetable oil, vanilla and melted chocolate, until well combined. Add eggs one at a time. Stir in flour, baking powder and salt. Add mini chocolate chips, if desired. Cover cookie dough with plastic wrap and refrigerate for at least 3 hours or overnight.
Preheat oven to 350 degrees.
Remove cookie dough from the refrigerator and form into teaspoon size balls. Roll balls into confectioners’ sugar and place on parchment lined cookie sheets, 2-inches apart.
Bake for 10-12 minutes. Remove from cookie sheet and cool on rack.
For Mocha Crinkles: Add 4 teaspoons instant coffee to the batter.