First prepare the crumble for the apple and toffee cake. Flour, sugar, salt, lemon sugar and almond flakes are mixed well and then stir in the possibly liquefied butter with a fork until nice crumbles are formed.
Grease a 28 cm cake tin well and sprinkle with breadcrumbs (or mixed almonds). Peel the apples, cut them into eighths and small slices, sprinkle only with lemon juice.
For the curd mixture, beat the eggs with the sugar and lemon sugar until creamy, then stir in the curd, mascarpone, semolina and 20 g flour. Pour 2/3 of the crumble mixture into the prepared pan and press down lightly.
Spread the carved apples on top. Pour the curd mixture on top and shake (gently) so that the mixture can settle. Spread the remaining crumble evenly over the top.
Bake in the preheated oven at 150 to 175 °C for about 1 1/4 hours. Allow to cool in the pan and then sprinkle with powdered sugar.