Mix sugar, flour, cocoa, vanilla sugar, baking powder, baking soda, and salt in a bowl.
Stir in melted butter, eggs, water, and coffee using a hand mixer until smooth.
Pour the batter into a baking tin lined with baking paper and bake for 30 minutes at 200 degrees Celsius (392 degrees Fahrenheit) on one of the lower racks.
Once the cake has cooled, you can add the topping.
Do this by simply mixing all the topping ingredients together with a hand mixer until you get a thick, creamy chocolate mixture.
Sprinkle with sprinkles, nuts, marshmallows or eat it as is ?