Heat your oven to 350°F/175°C. Line cupcake pan with cupcake papers.
In a medium bowl, combine the cocoa powder, flour, sugar, baking powder, baking soda, and salt. Stir to combine.
In a mixing bowl, add the vegetable oil and stout beer (be sure to pour the beer slowly into your measuring cup so you won't have too much foam), and vanilla.
Next, pour the flour mix into the beer mixture while mixing on medium speed. Continue mixing until the batter is smooth.
Spoon the cake batter into cupcake papers. Fill each about ¾ full. Bake for 25 minutes, until a toothpick inserted in the center of one of the cupcakes comes out clean.
When done, remove from oven and set aside to cool completely.
For the Chocolate Stout Frosting
To make the chocolate frosting, cream the vegan butter and cocoa powder with a mixer, for at least one minute.
Add the powdered sugar and mix until combined. Add the beer and vanilla and mix again until combined. Add the plant-based milk one tablespoon at a time until you reach a desired, spreadable consistency.
Scoop your frosting into a decorator bag and use a large star tip. Swirl the frosting on the top of each cupcake by starting in the middle and working your way around the cupcake from there.
* I was able to purchase a single can of stout beer