Pour cream into a mixing bowl. Wash the cup and dry. Whip the cream with the whisks of the hand mixer until stiff. Fold in 1 cup of sugar, vanilla sugar, salt and eggs.
Mix flour and baking powder and stir in briefly. Spread the dough on a baking tray (32 x 39 cm) lined with baking paper and pre-bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 15 minutes.
For the icing, melt butter, add 1/2 cup of sugar and 6 tablespoons of water and mix well. Fold in flaked almonds. Spread the almond icing evenly on the pastry sheet and bake for another 10-15 minutes at the same temperature until golden brown.
Remove and let it cool down. Serve with crème fraîche and plum jam.