Put 40 g sugar, icing sugar, salt and butter in pieces in a bowl and stir until creamy with the whisk of the hand mixer. Add the flour and work into a smooth dough with your hands. Cover and chill for about 30 minutes.
Wash and sort blackberries. Heat up with 2 tablespoons of sugar and 5 tablespoons of water in a pot. Cover and simmer for about 2 minutes. Stir starch with a little water until smooth, add to the blackberries while stirring and let simmer for about 1 minute. Remove from the heat, crush the blackberries slightly and let them cool down
Roll out the dough in portions on a floured work surface to a thickness of approx. 8 mm, kneading the dough again and again. Cut out 10 circles (approx. 6 cm Ø). Spread on a baking tray lined with baking paper. Bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 20 minutes until the biscuits are lightly browned. Let them cool down
Put the sour cream, cream and 2 tablespoons of sugar into a tall mixing bowl. Whip until stiff with the whisk of the hand mixer. Coarsely crumble 4 shortbreads (use the rest elsewhere) and divide into 4 glasses (approx. 250 ml each). Add approx. 1/4 of the blackberries. Loosely fold the rest of the blackberries, except for 4 tbsp, into the sour cream. Spread the cream into the glasses, add the remaining blackberries. Keep cool until serving
Picture 4: Decorate with lemon balm
Waiting time approx. 1 hour