In a bowl put the jam, sugar, eggs, spices and mix lightly. Add oil, orange juice, mineral water, salt powder, vanilla sugar. Homogenize then sift the flour mixed with baking powder and baking soda. Homogenize and pour 3.4 of the composition in a tray lined with baking paper. In the rest of the composition sift the cocoa, homogenize and pour unevenly on top. 50 minutes or until the toothpick test passes. Let the cake cool, then pour over the melted white chocolate with 2 tablespoons of milk in a saucepan over low heat.
Let the cake cool well before serving.