For the crumble: to make the crumble, mix butter, sugar, flour, about 2 tbsp. water and salt with the dough hooks of the hand mixer. Cool the crumble for at least 1 hour. For the batter: Whip butter, sugar, salt and vanilla sugar with the whisk of the hand mixer until creamy. Stir in the eggs one after the other. Stir in the lemon zest and juice. Sieve the flour and baking powder onto the mixture and continue beating for about 2 minutes. Distribute the sponge mixture on a baking tray lined with baking paper. Strain the apricots with a sieve and spread on the batter. Spread Darbo double-fruit apricot fruit spread on top along with the crumble. Bake the cake in a preheated oven at 200° C (circulating air 180° C, gas level 3) for about 35 minutes until golden brown. Let cool and cut into pieces.