Preheat an oven to 175 degrees C. Spray an 20x20cm baking tray or cake tin with cooking spray, and dust lightly with the 2 tablespoons cocoa powder. Place the coconut in the jar of a blender or food processor, and pulse to mince; set aside.
Whisk together the flour, sugar, 1/4 cup cocoa powder, baking powder, and salt. Stir in the chai, canola oil, and vanilla just until all ingredients are moistened. Fold in the coconut. Spread the batter in the prepared tray.
Bake in the preheated oven until the top is no longer shiny, about 20 minutes. Allow to cool for 1 hour before cutting.