Preheat the Oven: Start by preheating your oven to 180 degrees Celsius (or about 350 degrees Fahrenheit) with the top and bottom heat settings. Remember to grease a 26 cm springform pan slightly.

Mix Dry Ingredients: In a large mixing bowl, combine the flour, cocoa, espresso powder, sugar, vanilla sugar, baking powder, and salt.

Combine Wet Ingredients: Next, add the mineral water and neutral cooking oil to the dry ingredients. Using a whisk, quickly stir everything together until you have a smooth, lump-free batter.

Bake the Cake: Pour the cake batter into the prepared springform pan. Bake in the preheated oven for about 20-25 minutes or until a toothpick inserted in the center comes out clean. Once baked, let the cake cool completely.

Prepare the Ganache: For the ganache, chop the dark chocolate into small pieces and place it in a bowl. In a saucepan, heat the vegan whipped cream until it starts to bubble. Remove it from heat and pour it over the chopped chocolate. Allow it to sit for about 5 minutes before mixing until smooth.

Assemble the Cake: Halve the cooled cake horizontally to create two layers. Once the ganache has thickened, use a whisk to whip it until fluffy. Spread it generously between the two layers and on top of the cake.

Decorate: Finish with fresh berries and a sprinkle of chocolate asspel, if desired.