1 For the dough, combine the flour, salt and sugar on a work surface, form a well in the center and crack the eggs into it with 2-3 tablespoons of warm water. Cut the butter into pieces and chop all ingredients together with a knife, then knead into a dough with clean hands. Form the dough into a ball, wrap in plastic and chill in the refrigerator for 30 minutes. Preheat the oven to 180°C (approximately 350°F). Set a little bit of dough aside, then roll out the rest on a floured surface and line the greased baking pan with it, forming an edge around the top.
For the filling, rinse the apricots, blanch quickly in hot water, then rinse with cold water, peel, cut in half and remove pits. Press the apricot halves into the dough face down. Cream the butter and sugar until fluffly, then gradually add the vanilla sugar, rum, and lemon zest. Separate the eggs and beat the yolks into the butter one at a time. Stir in the semolina, baking powder and custard powder, followed by the cheese and sour cream. Beat the egg whites with 1 pinch of salt until stiff, then fold into the cream. Fill the pan with the cream and smooth the surface. Roll out the rest of the dough and cut into 1/2 cm (approximately 1/4 inch) strips and arrange in a grid over the cake. Bake the cake in a preheated oven for 30 minutes, then cover with tin foil and bake for 20-30 more minutes. Turn off the oven and let the cake stand inside for 10 minutes, then remove, loosen the cake pan and allow to cool completely.