In a bowl, whisk together all the dry ingredients like all-purpose flour, cocoa powder, baking powder, and salt.
In another bowl, add granulated sugar and oil and beat on medium speed for 2 minutes with a hand mixer or in a stand mixer till the mixture is light and fluffy. Add eggs and vanilla and mix till everything is well combined.
Now add the all-purpose flour mixture to this and mix gently until well combined.
Place the dough on a plastic wrap and refrigerate for 4 hours.
Preheat the oven to 180 degrees C and line a baking tray with butter paper or grease the tray with butter and sprinkle some dry flour.
Remove the dough from plastic wrap and make 2-inch size small balls. Roll each cookie dough ball in the icing sugar and place it on the baking tray. Roll the cookie balls twice into the icing powder so that they are densely coated and leave a space of 2 inches between each cookie.
Bake for 10 to 12 minutes. Once cooked, cool the cookies for a few minutes.
Serve warm or it can be stored in an air-tight container for 4 days. You can also freeze the cookies for up to a month.