Preheat the oven to 350 degrees Fahrenheit.
Mix together cocoa powder, sugar, butter, and oil until well combine.
Add in the egg and vanilla and fully incorporate.
In a separate bowl, whisk together flour, baking powder, and salt.
Slowly add flour mixture into the main mix. Make sure to fully incorporate but stop mixing as soon as combined not to over mix.
Fold in optional add-ins (see notes)
Make the dough into one inch balls for each cookie.
Bake for 10-12 minutes.