In a large bowl combine flours, baking powder, baking soda, cacao powder, gingerbread spice mix, salt, and sugar.
In another bowl combine soy milk, oil, and vinegar. Whisk until airy and fluffy. It should mimic the egg whites when beaten.
Pour the wet mixture into the dry and combine.
Pour the batter into a 9-inch baking pan lined with parchment paper. Bake at 400F (200°C) for about 35-40 minutes.
Cool down the cake completely and spread the plum jam on top. Melt the dark chocolate with vegan butter and pour it on top. Enjoy!