Preheat the oven to 180°C (350°F) and line a muffin tin with 12 paper liners.

In a mixing bowl, whisk together the flour, cocoa powder, and baking powder until combined.

In another mixing bowl, whisk together canola oil, brown sugar, and vanilla extract until well combined.

Pour in the Guinness or stout beer and mix until the wet ingredients are fully combined.

Gradually add the dry ingredients to the wet ingredients, whisking gently until just combined.

Divide the batter evenly among the prepared paper liners.

Bake for 18-20 minutes or until a toothpick inserted into the centre of a cupcake comes out clean.

Remove the cupcakes from the oven and let them cool in the tin for 5 minutes before transferring them to a wire rack to cool completely.

Make the buttercream: Using a hand mixer or a stand mixer with the paddle attachment fitted, beat dairy-free butter and vanilla for 1-2 minutes until creamy.

Add in half of the icing sugar and beat on medium until combined. Add in the cocoa powder and remaining icing sugar and continue to mix.

Add Guinness one tablespoon at a time, beating well after each addition, until the frosting reaches your desired consistency. If too thick, add a little more beer; if too thin, add extra icing sugar.

Once the cupcakes are cool, add the buttercream to a piping bag with your favourite tip and pipe swirls on top of each cupcake.