In a mixing bowl, mix together vegetable oil, sugar, and vanilla extract.
Add eggs one at a time; mix until well combined.
Mix in the cocoa powder.
Add the flour and baking powder; mix until smooth.Chill the dough for at least 4 hours in the refrigerator.Preheat oven to 350 F.Line a cookie sheet with greaseproof paper or a nonstick silicone mat.Scoop out a dough using an ice cream scooper and roll generously in confectioners sugar.