In a medium mixing bowl, add the granulate sugar, brown sugar, and canola oil. Mix until combined. Add the egg and vanilla and mix until combined and smooth.
Sift the flour, cocoa powder, baking powder, and salt over the wet ingredients. Stir just until no dry streaks remain. Note - I recommend sifting the dry ingredients over the wet ingredients to make sure there are no lumps - especially in the cocoa powder.
Stir in the chocolate chips until just combined. The dough will be sticky. Cover the bowl and place in the refrigerator to chill for at least an hour.
Preheat oven to 350F degrees and adjust the oven rack to the middle position. Line a baking sheet with a piece of parchment paper.
In a shallow dish, add the powdered sugar.
Using a medium cookie scoop (I use a #40), scoop even portions of the chilled cookie dough and gently roll the cookie dough into a ball with your hands (the dough may still be tacky). Then, roll each cookie dough ball liberally through the powdered sugar. Place the cookies at least 2 inches apart on the prepared baking sheet. Note - the number of cookies you get will depend on the size of the cookie scoop you use.
Bake the cookies for 10-12 minutes - or until the edges are firm and the middle still looks 'un-done'. Cool the cookies on the baking sheet set on a wire cooling rack for 5 minutes. Then transfer the cookies to the wire rack to cool completely. Enjoy!