Defrost 750 g raspberries. Line a fat pan (deep baking tray; approx. 32 x 39 cm) with baking paper. Preheat the oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Separate the eggs for the sponge cake.
Beat the egg whites and 1 pinch of salt with the whisks of the mixer until stiff, adding 150 g sugar and vanilla sugar. Stir in the egg yolks. Mix flour and baking powder, sieve onto the egg mixture and fold in.
Spread the mixture evenly on the fat pan. Spread 250 g frozen raspberries on top. Bake in a hot oven for about 15 minutes. Take out and turn onto a tea towel sprinkled with a little sugar, carefully peel off the baking paper.
Turn out the dough plate onto an oven rack and let it cool down.
Wash a lime in hot water, dry and finely grate the peel. Squeeze both limes. Soak 7 leaves in cold water and separately 2 leaves of gelatine. Puree thawed raspberries, pass through a sieve.
Weigh 200 g puree, mix with 2 tablespoons of sugar and set aside.
Mix quark with the rest of the purée, 200 g sugar, lime zest and juice. Squeeze 7 sheets of gelatine. Dissolve carefully in a small pot at very low heat. Stir in 2 tbsp. cream, then stir everything into the rest of the cream.
Whip cream until stiff, fold in. Squeeze out 2 sheets of gelatine, also dissolve and stir in 2 tbsp. of the purée that has been set aside, then stir everything into the rest of the purée. Chill both masses for 10-15 minutes.
When the masses start to gel, stir again. Cut the dough sheet in half crosswise. Spread half of the quark cream on each half, leaving a small rim all around. Pour the raspberry puree onto the cream, pull through several times with a fork, so that streaks appear.
Chill for at least 6 hours.