Beat the egg whites until stiff, while letting the sugar trickle in. Continue beating for 5-10 minutes until a smooth, firm, shiny mixture is formed. Sieve the starch, add vinegar and fold in
Draw 2 circles (20 cm Ø each) diagonally on a piece of baking paper, turn them over and place them on the baking tray. Spread the beaten egg white with a spoon on the two circles (2-3 cm thick)
Bake in a preheated oven (electric cooker: 100 °C/ convection oven: 75 °C/ gas: see manufacturer) for approx. 1 hour. Then reduce the temperature (electric oven: 80 °C/ convection oven: 60 °C/ gas: see manufacturer) and continue baking for approx. 1 hour. Let the meringue cool down in the oven when it is switched off
In the meantime, mix mascarpone and icing sugar. Wash the blackberries and drain well. Spread the mascarpone carefully on the two meringue slices and spread blackberries on top. Warm the jelly slightly and pour it over the blackberries in streaks. Dust with icing sugar. Place meringue slices on top of each other and serve immediately
Waiting time approx. 1 hour