Combine the sugar and oil. Mix in the eggs, one at a time.

Add the vanilla sugar, flour, and baking powder and mix until well combined.

In a separate bowl, dilute the cocoa and coffee grains in the hot water. Add this to the other mixture and combine until smooth.

Transfer to a lined muffin tin and bake at 350 degrees Fahrenheit (180 degrees Celsius) degrees for 20–25 minutes.

Mix ingredients until well combined. Smear over the cupcakes. If the batter becomes difficult to work with, add a little more hot water.