Preheat the oven to 180°C and line two cupcake trays with cupcake cases.
In a bowl of a stand mixer fitted with a whisk attachment, add the oil, and sugar. Beat at medium-high speed until well combined.
Sift together the flour, cocoa powder, and salt. Add the dry ingredients to the oil mixture, and beat at medium speed until just combined.
In a jug mix together the milk, brewed coffee, and vanilla. Slowly pour this into the cupcake batter, with the motor running at low speed. Scrape down the sides of the bowl and mix again. Ensuring the cupcake batter is well mixed and lump free.
Fill each cupcake case ¾ of the way up with cupcake batter and bake in a preheated oven for 12 - 15 minutes or until a toothpick inserted into the center of the cupcake comes out clean. Allow the cupcakes to cool completely.
Chocolate Buttercream
Add the icing sugar, cocoa powder, and butter to a bowl of a stand mixer fitted with a paddle attachment. Beat at medium speed until combined.
Add the vanilla to the milk and slowly pour this into the powdered sugar mixture with the mixer running at low speed.
Once all of the milk has been added scrape down the sides of the bowl. Mix the frosting again at medium-high speed for about 5 minutes or until the frosting is light and fluffy.
Fill a prepared piping bag with the chocolate frosting and pipe a swirl onto each cupcake. Decorate with sprinkles, and enjoy!