In a bowl, mix together the dry ingredients - flour, cocoa powder, baking soda and baking powder together.
In another bowl, beat well the butter and sugar (it should be creamy)
Add egg and vanilla extract to the butter sugar mixture and beat well.
Transfer the butter sugar egg mixture to the dry flour mixture and mix well.
Add the oil and chocolate chips to the cookie dough, mix everything well to form the final cookie dough.
Cover and refrigerate the cookie dough for at least 30 minutes since the chilled cookie dough gives you the best results.
When you are ready to bake the cookies, preheat oven to 350 degree Fahrenheit.
In a large baking sheet, drop spoon full of cookie dough to make medium sized cookies. Gently press them, but do not make it too flat, since the cookies will flatten out while baking. Leave enough space between the each drop of cookie dough, since the cookies will spread and take up more space as its baked. Since this cookie dough will give you about 24 cookies, you will probably need to bake the cookies in two batches. (Chill the remaining dough if not using right away, so you can bake it as needed (see notes how to use the dough if you have chilled the dough for a long time and not able to form the cookies due to hardening of dough)).
Bake for 12 to 14 minutes, allow the cookies to cool in the rack. Bake any remaining dough the same way (keep the remaining dough refrigerated until ready to use)