Wash the mirabelles, drain well and stone them. Drain mirabelle plums well from the jar and stone them. Mix fat, sugar and vanilla sugar with the whisk of the hand mixer for about 5 minutes until creamy. Add eggs one after the other, alternating with 1 tbsp. flour each, and mix well. Mix the rest of the flour and baking powder and finally stir in briefly together with the milk.
Place the dough on a greased, flour-strewn fat pan of the oven (32 x 39 cm) and spread evenly. Spread the mirabelles on the dough and sprinkle with almonds. Bake in the preheated oven, 2nd shelf from below (electric oven: 175 °C/ convection oven: 150 °C/ gas: level 2) for 40-50 minutes.
Mix icing sugar, lemon juice and 1-2 tablespoons of hot water. Sprinkle the finished mirabelle plum cake with icing while still hot. Let the cake cool down in the fat pan on a cake rack. Cut mirabelle plum cake into pieces, dust with icing sugar if necessary and serve with cream.