Separate eggs. Beat the egg whites and mineral water with the whisk of the hand mixer until stiff and finally add 125 g sugar. Beat the egg yolks one after the other. Mix flour, starch and baking powder, sieve onto the egg mixture and fold in carefully. Put the dough on a baking tray (32 x 39 cm) lined with baking paper and smooth it down. Bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 14 minutes. Remove the sponge cake from the oven, turn out on a damp tea towel and let it cool down
Soak gelatine in cold water. Clean, wash and halve the strawberries. Stir yoghurt with 50 ml advocaat, 50 g sugar and vanilla pulp until smooth. Squeeze the gelatine and dissolve. Mix gelatine with 50 ml advocaat. Stir into the yoghurt. Whip the cream with the whisk of the hand mixer until stiff and fold into the yoghurt
Cut the sponge in half crosswise. Cover one half with a baking frame and place strawberries on top. Spread yoghurt cream on the strawberries. Place the second half of the sponge cake on top and press it down a little. Chill for about 4 hours. Remove the cake from the baking frame with a hot knife, remove baking frame. Dust the cake with icing sugar, cut into 18 pieces and serve on a plate
waiting time approx. 4 1/2 hours