Preheat oven to 350°F (175°C). Line 2 cookie sheets or baking trays with parchment paper (baking paper).
In a medium-sized bowl, mix together the cocoa powder, white sugar, butter and vegetable oil. Beat in egg and vanilla until fully incorporated.
Add the flour, baking powder, and salt; stir the dry ingredients first before mixing them through the wet ingredients until a dough forms (do not over beat). Fold in the chocolate chips.
Scoop out 1-2 tablespoonful of dough with a cookie scoop (or small ice cream scoop), and place onto prepared baking sheets. Press them down as thick or thin as you want your cookies to come out.
Bake in hot preheated oven for 10-12 minutes. The cookies will come out soft from the oven but will harden up as they cool. (Be careful not to over bake as they will dry out.)
Allow to cool on the cookie sheet for 10 minutes before transferring to wire racks to cool.