First, heat up the milk until its hot, but not boiling, then add cocoa and espresso powder and set aside.

Heat up the oven at 175°C.

In a separate bowl, add oil, 1 egg, greek yogurt/sour cream and sugar, and mix it until it's smooth.

Stift in the flour, baking powder, salt and the cocoa-milk mixture. Gently whisk the ingredients until there's no flour streaks.

Pour the batter into the cupcake liners and bake for 15-20 minutes.

While its cooling, make the frosting.

To a bowl, add the room temperature butter and mix it until it's smooth.

Add espresso and 1/2 tsp vanilla (optional) and keep mixing.

Add powdered sugar and whip it until it's frosting consistency.

You can decorate the cupcakes once they're cooled off. Enjoy!