• Preheat the oven to 180 ℃. Line 2 x 12 cup muffin trays with paper cupcake liners,
• In the bowl of a stand mixer, add the eggs, sugar, brown sugar, oil and vanilla extract. Mix on a medium speed for 1 minute to combine.
• Add the cocoa powder, flour, baking powder, baking soda, salt and buttermilk. Mix on a low speed until everything is just combined. Don't overmix the batter.
• Fill each cupcake liner with enough batter so that they are just under half full.
• Bake the cupcakes for 16-18 minutes, until a skewer inserted in the middle comes out clean.
• Let cool for 5 minutes before transferring to a wire rack to finish cooling.

Chocolate Buttercream

• In the bowl of a stand mixer, add the butter and beat on a medium speed until creamy.
• Add the icing sugar, cocoa powder, cream, salt and vanilla. Beat on low for 30 seconds and then increase to a high speed for another minute.
• Transfer the buttercream to a piping bag fitted with a star nozzle and pipe onto each cupcake.
• Finish each cupcake with a sprinkling of colored or chocolate sprinkles.