For the dough, beat the fat, sugar and vanilla sugar with the whisk of the hand mixer until foamy. Add lemon zest. Stir in the eggs one by one. Mix flour, almonds and baking powder and stir into the egg-fat mixture in portions alternating with the milk.
Put the dough on a greased baking tray (32x37 cm) and smooth it down. Bake in the preheated oven (electric: 175 °C/ gas: level 2) for about 25 minutes. Let cool down on a cake rack.
For the cream, put 1/4 litre of water in a pot and add the jelly powder while stirring. Let it swell for about 10 minutes, heat it up briefly without boiling, and put it in a cool place. As soon as the jelly begins to gel, add mascarpone, sugar and lemon juice and stir in.
Whip cream and vanilla sugar until stiff and fold in. Spread the cream on the pastry base and smooth it down. Drain the peaches and cut into slices. Wash and clean the grapes and strawberries.
Pluck the grapes from the stems, cut them in half and remove the seeds. Halve or quarter strawberries. Sort blueberries, wash and drain. Spread the fruit on the cream and press down lightly. Place the cake glaze powder in a pot and mix with the grape juice.
Bring to the boil while stirring. Spread the cake glaze evenly over the fruit. Refrigerate the cake for about 1 hour until the glaze has set. Makes about 20 pieces.