Preheat the oven to 350 Fahrenheit. Line a baking sheet with parchment paper or a silicone liner, and set aside.
Combine the vegetable oil, brown sugar, and white sugar in a large bowl. Stir together to combine.
Add in the egg, vanilla, and milk, and stir until just combined.
In another bowl, whisk together the flour, cocoa, baking powder, baking soda, and salt.
Slowly add the dry ingredients into the wet ingredients while your stirring, until they are just combined.
Add in the hot water and stir it into the batter until it is all combined.
Carefully scoop the batter by the 1 1/2 TBS full onto the prepared baking sheet. Keep the batter balls about 2 inches apart, as they well spread while they bake.
Bake the pan in the preheated oven until the "cookie" tops look set and a toothpick can be inserted and comes out clean. Between 9 and 11 minutes.
Let the whoope pies cool on the baking pan for about 5 to 10 minutes, then transfer them to a cooling rack to cool completely.