Beat the eggs and 125 g sugar with the whisk of the hand mixer for 8-10 minutes until thick and creamy. Stir in milk. Mix flour and baking powder and fold into the egg cream. Line a baking tray (32 x 39 cm) with baking paper. Put the mixture on top and spread. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 10 minutes.
Turn out the sponge cake plate onto a tea towel sprinkled with sugar. Remove baking paper, roll up the plate with the cloth and let it cool down. Bring orange juice and 100 g sugar to the boil in a pan, simmer for 5 minutes. Wash and slice the kumquats. Add to syrup and simmer for 2-4 minutes. Let it cool down. Drain the kumquats in a sieve and collect the syrup. Soak gelatine in cold water. Stir curd cheese, 50 g sugar, collected syrup and vanillin sugar until smooth. Squeeze the gelatine, dissolve and mix with 2 tablespoons of cream. Then stir everything into the remaining cream.
Drain the kumquats in a sieve and collect the syrup. Soak gelatine in cold water. Stir curd cheese, 50 g sugar, collected syrup and vanillin sugar until smooth. Squeeze the gelatine, dissolve and mix with 2 tablespoons of cream. Then stir everything into the remaining cream. Whip cream until stiff and fold in. Unroll the sponge again. Pour curd mixture on top and smooth it down. Spread the kumquats, except for 2-3 tablespoons for decoration, on the cream. Roll everything up and refrigerate for about 4 hours. Dust the sponge roll with icing sugar and decorate with kumquats that have been set aside
Whip cream until stiff and fold in. Unroll the sponge again. Pour curd mixture on top and smooth it down. Spread the kumquats, except for 2-3 tablespoons for decoration, on the cream. Roll everything up and refrigerate for about 4 hours. Dust the sponge roll with icing sugar and decorate with kumquats that have been set aside