In a small bowl, mix the flour, baking powder, and salt and stir. Set aside.
In a large bowl, mix the cocoa powder, sugar, and vegetable oil. Add the eggs and peppermint extract and beat until combined.
Fold the dry mixture into the wet mixture and stir. Add the white chocolate chips and stir until just combined. Cover and chill overnight in the fridge (or 3 hours at the minimum).
Once chilled, preheat the oven to 350°F and bring the cookie dough to room temperature.
Roll the dough into 1 tbsp balls and toss in powdered sugar until coated. Place on a lined cookie sheet.
Bake for 11-12 minutes. The cookies will harden as they cool. Let cool for 5-10 minutes before transferring to a cooling rack.
