Drain the sour cherries. Preheat the oven to 180 degrees Celsius. Put all the ingredients for the sponge cake base - except for the sour cherries and cocoa powder - in a large bowl and stir briefly to form a fairly smooth batter. Do not stir too much, otherwise the dough will lose its rising power.

Grease a deep baking sheet or an oven pan (approx. 32x23cm) with a little oil or line it with baking paper. Pour in half of the batter. Mix the other half of the batter with the cocoa powder and pour on top. Spread the drained sour cherries on top and bake everything for about 35 minutes. Remove from the oven and allow to cool down.

For the vegan buttercream, stir the starch with a small dash of the plant milk until smooth. Bring the rest of the milk to the boil. Stir in the starch, bring to the boil briefly and cover and let cool down at room temperature.

When the vegan butter is brought to room temperature, whip it with the sugar until creamy. Gradually stir in the cooled pudding mixture. Spread the cream evenly on the cooled dough and let it set in the refrigerator.

Heat the plant milk for the glaze. Take off the heat, add the chopped chocolate, let it melt and stir until smooth. Spread carefully on the cooled and tightened buttercream layer. Let cool down as well. If you like, when the glaze is slightly tightened, use a fork to make a wave pattern in it.